cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A360759 a(n) = Sum_{d|n} d^(d+n/d) * binomial(d,n/d).

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%I A360759 #21 Aug 02 2023 02:00:40
%S A360759 1,16,243,4112,78125,1680345,40353607,1073766400,31381060338,
%T A360759 1000000781250,34522712143931,1283918489808640,51185893014090757,
%U A360759 2177953338656796883,98526125335697265625,4722366482899710050304,239072435685151324847153
%N A360759 a(n) = Sum_{d|n} d^(d+n/d) * binomial(d,n/d).
%H A360759 Winston de Greef, <a href="/A360759/b360759.txt">Table of n, a(n) for n = 1..383</a>
%F A360759 G.f.: Sum_{k>0} k^k * ( (1 + k*x^k)^k - 1 ).
%F A360759 If p is prime, a(p) = p^(p+2).
%t A360759 a[n_] := DivisorSum[n, #^(# + n/#) * Binomial[#, n/#] &]; Array[a, 20] (* _Amiram Eldar_, Aug 02 2023 *)
%o A360759 (PARI) a(n) = sumdiv(n, d, d^(d+n/d)*binomial(d, n/d));
%o A360759 (PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=1, N, k^k*((1+k*x^k)^k-1)))
%Y A360759 Cf. A318636, A327238, A338685, A338693, A338694.
%Y A360759 Cf. A360712.
%K A360759 nonn
%O A360759 1,2
%A A360759 _Seiichi Manyama_, Feb 19 2023