Английская Википедия:115 (number)

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Шаблон:Use dmy dates Шаблон:Infobox number 115 (one hundred [and] fifteen) is the natural number following 114 and preceding 116.

In mathematics

115 has a square sum of divisors:[1]

<math>\sigma(115)=1+5+23+115=144=12^2.</math>

There are 115 different rooted trees with exactly eight nodes,[2] 115 inequivalent ways of placing six rooks on a 6 × 6 chess board in such a way that no two of the rooks attack each other,[3] and 115 solutions to the stamp folding problem for a strip of seven stamps.[4]

115 is also a heptagonal pyramidal number.[5] The 115th Woodall number,

<math>115\cdot 2^{115}-1=4\;776\;913\;109\;852\;041\;418\;248\;056\;622\;882\;488\;319,</math>

is a prime number.[6] 115 is the sum of the first five heptagonal numbers.

See also

References

Шаблон:Reflist

Шаблон:Integers