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836 (number)
836 (eight hundred ndthirty-six) is the natural number following 835 and preceding 837. In mathematics The factorization of 836 is , so its proper factors are 1, 2, 4, 11, 19, 22, 38, 44, 76, 209, and 418. They sum to 844. As this is greater than 836, it is an abundant number, but no subset sums to 836, so it is not a semiperfect number; therefore it is a weird number. Besides, 836 is the smallest weird number that is also an untouchable number, i.e. there is no ''n'' such that the sum of proper factors of ''n'' equals 836. (The only smaller weird number 70 is not untouchable, since σ(134) − 134 = 70) See also * 836 (year) * 836 Jole (asteroid) * 836th Air Division, an inactive United States Air Force organization * 836 Naval Air Squadron 836 Squadron was a squadron of the Royal Navy's Fleet Air Arm. History 836 Naval Air Squadron officially formed for the first time at Palisadoes, Jamaica, in March 1942 as a torpedo bomber reconnaissance squadron flying the Fairey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Number
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country"). Numbers used for counting are called ''cardinal numbers'', and numbers used for ordering are called ''ordinal numbers''. Natural numbers are sometimes used as labels, known as '' nominal numbers'', having none of the properties of numbers in a mathematical sense (e.g. sports jersey numbers). Some definitions, including the standard ISO 80000-2, begin the natural numbers with , corresponding to the non-negative integers , whereas others start with , corresponding to the positive integers Texts that exclude zero from the natural numbers sometimes refer to the natural numbers together with zero as the whole numbers, while in other writings, that term is used instead for the integers (including negative integers). The natural numbers form a set. Many other number sets are built by succ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
800 (number)
800 (eight hundred) is the natural number following 799 and preceding 801. It is the sum of four consecutive primes (193 + 197 + 199 + 211). It is a Harshad number, an Achilles number and the area of a square with diagonal 40. Integers from 801 to 899 800s * 801 = 32 × 89, Harshad number, number of clubs patterns appearing in 50 × 50 coins * 802 = 2 × 401, sum of eight consecutive primes (83 + 89 + 97 + 101 + 103 + 107 + 109 + 113), nontotient, happy number, sum of 4 consecutive triangular numbers (171 + 190 + 210 + 231) * 803 = 11 × 73, sum of three consecutive primes (263 + 269 + 271), sum of nine consecutive primes (71 + 73 + 79 + 83 + 89 + 97 + 101 + 103 + 107), Harshad number, number of partitions of 34 into Fibonacci parts * 804 = 22 × 3 × 67, nontotient, Harshad number, ** "The 804" is a local nickname for the Greater Richmond Region of the U.S. state of Virginia, derived from its telephone area code (although the area code covers a larger area). * 805 = 5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abundant Number
In number theory, an abundant number or excessive number is a number for which the sum of its proper divisors is greater than the number. The integer 12 is the first abundant number. Its proper divisors are 1, 2, 3, 4 and 6 for a total of 16. The amount by which the sum exceeds the number is the abundance. The number 12 has an abundance of 4, for example. Definition A number ''n'' for which the ''sum'' ''of'' ''divisors'' ''σ''(''n'') > 2''n'', or, equivalently, the sum of proper divisors (or aliquot sum) ''s''(''n'') > ''n''. Abundance is the value ''σ''(''n'') − ''2n'' (or ''s''(''n'') − ''n''). Examples The first 28 abundant numbers are: :12, 18, 20, 24, 30, 36, 40, 42, 48, 54, 56, 60, 66, 70, 72, 78, 80, 84, 88, 90, 96, 100, 102, 104, 108, 112, 114, 120, ... . For example, the proper divisors of 24 are 1, 2, 3, 4, 6, 8, and 12, whose sum is 36. Because 36 is greater than 24, the number 24 is abundant. Its abundance is 36 − 24 = 12. Prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiperfect Number
In number theory, a semiperfect number or pseudoperfect number is a natural number ''n'' that is equal to the sum of all or some of its proper divisors. A semiperfect number that is equal to the sum of all its proper divisors is a perfect number. The first few semiperfect numbers are: 6, 12, 18, 20, 24, 28, 30, 36, 40, ... Properties * Every multiple of a semiperfect number is semiperfect.Zachariou+Zachariou (1972) A semiperfect number that is not divisible by any smaller semiperfect number is called ''primitive''. * Every number of the form 2''m''''p'' for a natural number ''m'' and an odd prime number ''p'' such that ''p'' < 2''m''+1 is also semiperfect. ** In particular, every number of the form 2''m''(2''m''+1 − 1) is semiperfect, and indeed perfect if 2''m''+1 − 1 is a |
Weird Number
In number theory, a weird number is a natural number that is abundant but not semiperfect. In other words, the sum of the proper divisors (divisors including 1 but not itself) of the number is greater than the number, but no subset of those divisors sums to the number itself. Examples The smallest weird number is 70. Its proper divisors are 1, 2, 5, 7, 10, 14, and 35; these sum to 74, but no subset of these sums to 70. The number 12, for example, is abundant but ''not'' weird, because the proper divisors of 12 are 1, 2, 3, 4, and 6, which sum to 16; but 2 + 4 + 6 = 12. The first few weird numbers are : 70, 836, 4030, 5830, 7192, 7912, 9272, 10430, 10570, 10792, 10990, 11410, 11690, 12110, 12530, 12670, 13370, 13510, 13790, 13930, 14770, ... . Properties Infinitely many weird numbers exist. For example, 70''p'' is weird for all primes ''p'' ≥ 149. In fact, the set of weird numbers has positive asymptotic density. It is not known if any ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Untouchable Number
An untouchable number is a positive integer that cannot be expressed as the sum of all the proper divisors of any positive integer (including the untouchable number itself). That is, these numbers are not in the image of the aliquot sum function. Their study goes back at least to Abu Mansur al-Baghdadi (circa 1000 AD), who observed that both 2 and 5 are untouchable. Examples For example, the number 4 is not untouchable as it is equal to the sum of the proper divisors of 9: 1 + 3 = 4. The number 5 is untouchable as it is not the sum of the proper divisors of any positive integer: 5 = 1 + 4 is the only way to write 5 as the sum of distinct positive integers including 1, but if 4 divides a number, 2 does also, so 1 + 4 cannot be the sum of all of any number's proper divisors (since the list of factors would have to contain both 4 and 2). The first few untouchable numbers are: : 2, 5, 52, 88, 96, 120, 124, 146, 162, 188, 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
70 (number)
70 (seventy) is the natural number following 69 and preceding 71. In mathematics 70 is: * a sphenic number because it factors as 3 distinct primes. * a Pell number. * the seventh pentagonal number. * the fourth tridecagonal number. * the fifth pentatope number. * the number of ways to choose 4 objects out of 8 if order does not matter. This makes it a central binomial coefficient. * the smallest weird number, a natural number that is abundant but not semiperfect. * a palindromic number in bases 9 (779), 13 (5513) and 34 (2234). * a Harshad number in bases 6, 8, 9, 10, 11, 13, 14, 15 and 16. * an Erdős–Woods number, since it is possible to find sequences of 70 consecutive integers such that each inner member shares a factor with either the first or the last member. The sum of the first 24 squares starting from 1 is 70 = 4900, i.e. a square pyramidal number. This is the only non trivial solution to the cannonball problem and relates 70 to the Leech lattice and thus s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
836 Jole
836 Jole ('' prov. designation:'' ''or'' ) is a bright background asteroid from the inner regions of the asteroid belt. It was discovered on 23 September 1916, by German astronomer Max Wolf at the Heidelberg Observatory in southwest Germany. The stony S-type asteroid has a rotation period of 9.6 hours and measures approximately in diameter. It was named after Iole, wife of Heracles from Greek mythology. Orbit and classification Located in the orbital region of the Flora family, ''Jole'' is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. It orbits the Sun in the inner asteroid belt at a distance of 1.8–2.6 AU once every 3 years and 3 months (1,184 days; semi-major axis of 2.19 AU). Its orbit has an eccentricity of 0.18 and an inclination of 5 ° with respect to the ecliptic. The asteroid was first observed as A903 QA at Heidelberg Observatory on 24 August 1903, wher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
836th Air Division
The 836th Air Division is an inactive United States Air Force organization. Its last assignment was with Tactical Air Command (TAC) at Davis-Monthan Air Force Base, Arizona, where it was inactivated on 1 May 1992. The division had been activated at Davis-Monthan in January 1981 to replace Tactical Training, Davis-Monthan. Its primary mission was training for Fairchild A-10 Thunderbolt II and BGM-109G Gryphon crews. The 602d Tactical Control Wing moved to Davis-Monthan, and the division's training mission expanded to include Forward Air Controllers flying several aircraft. The BGM-109 mission ended with the signing of the Intermediate-Range Nuclear Forces Treaty. In 1989, division elements participated in Operation Just Cause. The division was inactivated with the implementation of the Objective Wing reorganization, which established a single wing on each Air Force Base. The division was first activated in 1957 at Langley Air Force Base, Virginia as the command headqua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
836 Naval Air Squadron
836 Squadron was a squadron of the Royal Navy's Fleet Air Arm. History 836 Naval Air Squadron officially formed for the first time at Palisadoes, Jamaica, in March 1942 as a torpedo bomber reconnaissance squadron flying the Fairey Swordfish. It operated from HMS ''Buzzard'' at Palisadoes, Jamaica, in spring 1942, and it subsequently embarked on the Woolworth carrier in June 1942 for the UK, where it joined RAF Coastal Command in January 1943 for operations in the English Channel from RAF Thorney Island. 836 returned aboard HMS ''Biter'' to be re-formed to provide personnel and aircraft for the MAC ships, 836 was later based at Maydown, known as HMS ''Shrike'', in Northern Ireland, not far from Lough Foyle, and commanded by Acting Lieutenant Commander Ransford Slater. He took command in July 1942 and worked up the squadron at Thorney Island until March 1943 when it was based at Machrihanish. Lieutenant Commander Slater Slater had personally led the squadron's 'A' flight in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pi Arietis
Pi Arietis, Latinized from π Arietis, is the Bayer designation for a multiple star system in the northern constellation of Aries. Based upon parallax measurements made during the Hipparcos mission, this system is approximately distant from Earth and has an apparent visual magnitude of 5.21. This is bright enough to be faintly seen with the naked eye. The primary member of this system is a massive, B-type main sequence star with a stellar classification of B6 V. It is a close spectroscopic binary with an orbital period of 3.854 days, an eccentricity of 0.04, and a combined visual magnitude of 5.30. At an angular separation of 3.28 arcseconds is a magnitude 8.46 A-type main sequence star with a classification of A0 Vp. Finally, a fourth member of the system is a magnitude 11.0 F-type main sequence star with a classification of F8V at an angular separation of 25.2 arcseconds from the primary. Name This star, along with δ Ari, ε Ari, ζ Ari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
