218 (two hundred
ndeighteen) is the
natural number
In mathematics, the natural numbers are the numbers 0, 1, 2, 3, and so on, possibly excluding 0. Some start counting with 0, defining the natural numbers as the non-negative integers , while others start with 1, defining them as the positive in ...
following
217 and preceding
219.
In mathematics
*
Mertens function
In number theory, the Mertens function is defined for all positive integers ''n'' as
: M(n) = \sum_^n \mu(k),
where \mu(k) is the Möbius function. The function is named in honour of Franz Mertens. This definition can be extended to positive r ...
(218) = 3, a record high.
*218 is
nontotient
In number theory, a nontotient is a positive integer ''n'' which is not a totient number: it is not in the range of Euler's totient function φ, that is, the equation φ(''x'') = ''n'' has no solution ''x''. In other words, ''n'' is a nontotie ...
and also
noncototient
In number theory, a noncototient is a positive integer that cannot be expressed as the difference between a positive integer and the number of coprime integers below it. That is, , where stands for Euler's totient function
In number theory ...
.
*218 is the number of inequivalent ways to color the 12 edges of a cube using at most 2 colors, where two colorings are equivalent if they differ only by a rotation of the cube.
*There are 218 nondegenerate
Boolean function
In mathematics, a Boolean function is a function whose arguments and result assume values from a two-element set (usually , or ). Alternative names are switching function, used especially in older computer science literature, and truth functi ...
s of 3 variables.
*The number of surface points on a 7
3 cube.
See also
*The years
218
Year 218 ( CCXVIII) was a common year starting on Thursday of the Julian calendar. At the time, it was known as the Year of the Consulship of Severus and Adventus (or, less frequently, year 971 ''Ab urbe condita''). The denomination 218 for th ...
and
218 BC
__NOTOC__
Year 218 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Scipio and Longus (or, less frequently, year 536 ''Ab urbe condita''). The denomination 218 BC for this year has been u ...
References
Integers
{{Num-stub