# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/

Search: id:a327238
Showing 1-1 of 1

%I A327238 #32 Feb 19 2023 08:47:30
%S A327238 1,4,9,20,25,63,49,160,108,350,121,940,169,1225,1475,2304,289,7560,
%T A327238 361,8025,12446,7139,529,58192,3750,13858,61965,102655,841,191181,961,
%U A327238 318464,220704,40460,354172,1304370,1369,63175,629863,4012608,1681,1916733,1849
%N A327238 Expansion of Sum_{k>=1} ((1 + k * x^k)^k - 1).
%H A327238 Seiichi Manyama, <a href="/A327238/b327238.txt">Table of n, a(n) for n = 1..10000</a>
%F A327238 a(n) = Sum_{d|n} (n/d)^d * binomial(n/d,d).
%F A327238 a(p) = p^2, where p is prime.
%t A327238 nmax = 43; CoefficientList[Series[Sum[((1 + k x^k)^k - 1), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
%t A327238 Table[DivisorSum[n, (n/#)^# Binomial[n/#, #] &], {n, 1, 43}]
%o A327238 (PARI) a(n)={sumdiv(n, d, (n/d)^d * binomial(n/d,d))} \\ _Andrew Howroyd_, Sep 14 2019
%Y A327238 Cf. A055225, A056045, A318636, A327124.
%K A327238 nonn,look
%O A327238 1,2
%A A327238 _Ilya Gutkovskiy_, Sep 14 2019

# Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE