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Results tagged with divisors-multiples
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user 231922
For questions on divisors and multiples, mainly but not exclusively of integers, and related and derived notions such as sums of divisors, perfect numbers and so on.
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Mysterious recursion for the A005225
Let $a(n)$ be A005225 i.e. number of permutations of length $n$ with equal cycles. Here
$$
a(n)=n!\sum\limits_{d|n}\frac{1}{d!(\frac{n}{d})^d}
$$
Let
$$
R(n,q,z)=(q+1)R(n-1,q+1,z)+\sum\limits_{j=0}^{ …
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