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Perfect Number
In number theory, a perfect number is a positive integer that is equal to the sum of its positive divisors, excluding the number itself. For instance, 6 has divisors 1, 2 and 3 (excluding itself), and 1 + 2 + 3 = 6, so 6 is a perfect number. The sum of divisors of a number, excluding the number itself, is called its aliquot sum, so a perfect number is one that is equal to its aliquot sum. Equivalently, a perfect number is a number that is half the sum of all of its positive divisors including itself; in symbols, \sigma_1(n)=2n where \sigma_1 is the sum-of-divisors function. For instance, 28 is perfect as 1 + 2 + 4 + 7 + 14 = 28. This definition is ancient, appearing as early as Euclid's ''Elements'' (VII.22) where it is called (''perfect'', ''ideal'', or ''complete number''). Euclid also proved a formation rule (IX.36) whereby q(q+1)/2 is an even perfect number whenever q is a prime of the form 2^p-1 for positive integer p—what is now called a Mersenne prime. Two millenni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Perfect Number Cuisenaire Rods 6
Perfect commonly refers to: * Perfection, completeness, excellence * Perfect (grammar), a grammatical category in some languages Perfect may also refer to: Film * ''Perfect'' (1985 film), a romantic drama * ''Perfect'' (2018 film), a science fiction thriller Literature * ''Perfect'' (Friend novel), a 2004 novel by Natasha Friend * ''Perfect'' (Hopkins novel), a young adult novel by Ellen Hopkins * ''Perfect'' (Joyce novel), a 2013 novel by Rachel Joyce * ''Perfect'' (Shepard novel), a Pretty Little Liars novel by Sara Shepard * ''Perfect'', a young adult science fiction novel by Dyan Sheldon Music * Perfect interval, in music theory * Perfect Records, a record label Artists * Perfect (musician) (born 1980), reggae singer * Perfect (Polish band) * Perfect (American band), an American alternative rock group Albums * ''Perfect'' (Intwine album) (2004) * ''Perfect'' (Half Japanese album) (2016) * ''perfecT'', an album by Sam Shaber * ''Perfect'', an album by True ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Triangular Number
A triangular number or triangle number counts objects arranged in an equilateral triangle. Triangular numbers are a type of figurate number, other examples being square numbers and cube numbers. The th triangular number is the number of dots in the triangular arrangement with dots on each side, and is equal to the sum of the natural numbers from 1 to . The sequence of triangular numbers, starting with the 0th triangular number, is (This sequence is included in the On-Line Encyclopedia of Integer Sequences .) Formula The triangular numbers are given by the following explicit formulas: T_n= \sum_^n k = 1+2+3+ \dotsb +n = \frac = , where \textstyle is a binomial coefficient. It represents the number of distinct pairs that can be selected from objects, and it is read aloud as " plus one choose two". The first equation can be illustrated using a visual proof. For every triangular number T_n, imagine a "half-square" arrangement of objects corresponding to the triangular n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Ibn Al-Haytham
Ḥasan Ibn al-Haytham, Latinized as Alhazen (; full name ; ), was a medieval mathematician, astronomer, and physicist of the Islamic Golden Age from present-day Iraq.For the description of his main fields, see e.g. ("He is one of the principal Arab mathematicians and, without any doubt, the best physicist.") , ("Ibn al-Ḥaytam was an eminent eleventh-century Arab optician, geometer, arithmetician, algebraist, astronomer, and engineer."), ("Ibn al-Haytham (d. 1039), known in the West as Alhazan, was a leading Arab mathematician, astronomer, and physicist. His optical compendium, Kitab al-Manazir, is the greatest medieval work on optics.") Referred to as "the father of modern optics", he made significant contributions to the principles of optics and visual perception in particular. His most influential work is titled '' Kitāb al-Manāẓir'' (Arabic: , "Book of Optics"), written during 1011–1021, which survived in a Latin edition. Ibn al-Haytham was an early propo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Wolfram Alpha
WolframAlpha ( ) is an answer engine developed by Wolfram Research. It answers factual queries by computing answers from externally sourced data. WolframAlpha was released on May 18, 2009 and is based on Wolfram's earlier product Wolfram Mathematica, a technical computing platform. WolframAlpha gathers data from academic and commercial websites such as the CIA's ''The World Factbook'', the United States Geological Survey, a Cornell University Library publication called ''All About Birds'', ''Chambers Biographical Dictionary'', Dow Jones, the ''Catalogue of Life'', CrunchBase, Best Buy, and the FAA to answer queries. A Spanish version was launched in 2022. Technology Overview Users submit queries and computation requests via a text field. WolframAlpha then computes answers and relevant visualizations from a knowledge base of curated, structured data that come from other sites and books. It is able to respond to particularly phrased natural language fact-based questions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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43,112,609 (number)
43,112,609 (forty-three million, one hundred twelve thousand, six hundred nine) is the natural number following 43,112,608 and preceding 43,112,610. In mathematics 43,112,609 is a prime number. Moreover, it is the exponent of the 47th Mersenne prime, equal to M43,112,609 = 243,112,609 − 1, a prime number with 12,978,189 decimal digits. It was discovered on August 23, 2008 by Edson Smith, a volunteer of the Great Internet Mersenne Prime Search. The 45th Mersenne prime, M37,156,667 = 237,156,667 − 1, was discovered two weeks later on September 6, 2008, marking the shortest chronological gap between discoveries of Mersenne primes since the formation of the online collaborative project in 1996. It was the first time since 1963 when two Mersenne primes were discovered less than 30 days apart from each other. Less than a year later, on June 4, 2009, the 46th Mersenne prime, M42,643,801 = 242,643,801 − 1, was discovered by Odd Magnar Strindmo, a GIMPS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Sophie Germain Prime
In number theory, a prime number ''p'' is a if 2''p'' + 1 is also prime. The number 2''p'' + 1 associated with a Sophie Germain prime is called a . For example, 11 is a Sophie Germain prime and 2 × 11 + 1 = 23 is its associated safe prime. Sophie Germain primes are named after French mathematician Sophie Germain, who used them in her investigations of Fermat's Last Theorem. One attempt by Germain to prove Fermat’s Last Theorem was to let ''p'' be a prime number of the form 8''k'' + 7 and to let ''n'' = ''p'' – 1. In this case, x^n + y^n = z^n is unsolvable. Germain’s proof, however, remained unfinished. Through her attempts to solve Fermat's Last Theorem, Germain developed a result now known as Germain's Theorem which states that if ''p'' is an odd prime and 2''p'' + 1 is also prime, then ''p'' must divide ''x'', ''y'', or ''z.'' Otherwise, x^n + y^n \neq z^n. This case where ''p'' does not divide ''x'', ''y'', or ''z'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Marin Mersenne
Marin Mersenne, OM (also known as Marinus Mersennus or ''le Père'' Mersenne; ; 8 September 1588 – 1 September 1648) was a French polymath whose works touched a wide variety of fields. He is perhaps best known today among mathematicians for Mersenne prime numbers, those which can be written in the form for some integer . He also developed Mersenne's laws, which describe the harmonics of a vibrating string (such as may be found on guitars and pianos), and his seminal work on music theory, '' Harmonie universelle'', for which he is referred to as the "father of acoustics". Mersenne, an ordained Catholic priest, had many contacts in the scientific world and has been called "the center of the world of science and mathematics during the first half of the 1600s" and, because of his ability to make connections between people and ideas, "the post-box of Europe". He was also a member of the Minim religious order and wrote and lectured on theology and philosophy. Life Mersenne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Prime Number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, or , involve 5 itself. However, 4 is composite because it is a product (2 × 2) in which both numbers are smaller than 4. Primes are central in number theory because of the fundamental theorem of arithmetic: every natural number greater than 1 is either a prime itself or can be factorized as a product of primes that is unique up to their order. The property of being prime is called primality. A simple but slow method of checking the primality of a given number n, called trial division, tests whether n is a multiple of any integer between 2 and \sqrt. Faster algorithms include the Miller–Rabin primality test, which is fast but has a small chance of error, and the AKS primality test, which alw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Pietro Cataldi
Pietro Antonio Cataldi (15 April 1548, Bologna – 11 February 1626, Bologna) was an Italian mathematician. A citizen of Bologna, he taught mathematics and astronomy and also worked on military problems. His work included the development of continued fractions and a method for their representation. He was one of many mathematicians who attempted to prove Euclid's fifth postulate. Cataldi discovered the sixth and seventh perfect numbers by 1588.Caldwell, Chris''The largest known prime by year'' His discovery of the 6th, that corresponding to p=17 in the formula Mp=2p-1, exploded a many-times repeated number-theoretical myth that the perfect numbers had units digits that invariably alternated between 6 and 8. (Until Cataldi, 19 authors going back to Nicomachus are reported to have made the claim, with a few more repeating this afterward, according to L.E.Dickson's '' History of the Theory of Numbers''). Cataldi's discovery of the 7th (for p=19) held the record for the largest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bayerische Staatsbibliothek
The Bavarian State Library (german: Bayerische Staatsbibliothek, abbreviated BSB, called ''Bibliotheca Regia Monacensis'' before 1919) in Munich is the central " Landesbibliothek", i. e. the state library of the Free State of Bavaria, the biggest universal and research library in Germany and one of Europe's most important universal libraries. With its collections currently comprising around 10.89 million books (as of 2019), it ranks among the best research libraries worldwide. Moreover, its historical stock encompasses one of the most important manuscript collections of the world, the largest collection of incunabula worldwide, as well as numerous further important special collections. Its collection of historical prints before 1850 number almost one million units. The legal deposit law has been in force since 1663, regulating that two copies of every printed work published in Bavaria have to be submitted to the Bayerische Staatsbibliothek. This law is still applicable today. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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City Of God (book)
''On the City of God Against the Pagans'' ( la, De civitate Dei contra paganos), often called ''The City of God'', is a book of Christian philosophy written in Latin by Augustine of Hippo in the early 5th century AD. The book was in response to allegations that Christianity brought about the decline of Rome and is considered one of Augustine's most important works, standing alongside '' The Confessions'', '' The Enchiridion'', '' On Christian Doctrine'', and '' On the Trinity''. As a work of one of the most influential Church Fathers, ''The City of God'' is a cornerstone of Western thought, expounding on many questions of theology, such as the suffering of the righteous, the existence of evil, the conflict between free will and divine omniscience, and the doctrine of original sin. Background The sack of Rome by the Visigoths in 410 left Romans in a deep state of shock, and many Romans saw it as punishment for abandoning traditional Roman religion in favor of Christiani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Didymus The Blind
Didymus the Blind (alternatively spelled Dedimus or Didymous) (c. 313398) was a Christian theologian in the Church of Alexandria, where he taught for about half a century. He was a student of Origen, and, after the Second Council of Constantinople condemned Origen, Didymus's works were not copied. Many of his writings are lost, but some of his commentaries and essays survive. He was seen as intelligent and a good teacher. Early life and education Didymus became blind at the age of four, before he had learned to read. He was a loyal follower of Origen, and opposed Arian and Macedonian teachings. Despite his blindness, Didymus excelled in scholarship because of his incredible memory. He found ways to help blind people to read, experimenting with carved wooden letters similar to Braille systems used by the blind today. He recalled and contemplated information while others slept. Teacher in Alexandria According to Rufinus, Didymus was "a teacher in the Church school", who was "appro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |