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.
%I A356688 #16 Aug 24 2022 12:09:20 %S A356688 1,1,66,21225,18952156,36175231585,126556309395486,733064060959310689, %T A356688 6540867625730306094360,85180334386943946887707617, %U A356688 1552697061493449955344530003290,38315904135534199560725372265381721,1245605749857294018587318829355458646068 %N A356688 a(n) = n! * Sum_{k=0..n} k^(3*n)/k!. %H A356688 Seiichi Manyama, <a href="/A356688/b356688.txt">Table of n, a(n) for n = 0..149</a> %F A356688 E.g.f.: Sum_{k>=0} (k^3 * x)^k / (k! * (1 - k^3 * x)). %t A356688 a[n_] := n! * Sum[k^(3*n)/k!, {k, 0, n}]; a[0] = 1; Array[a, 13, 0] (* _Amiram Eldar_, Aug 23 2022 *) %o A356688 (PARI) a(n) = n!*sum(k=0, n, k^(3*n)/k!); %o A356688 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(sum(k=0, N, (k^3*x)^k/(k!*(1-k^3*x))))) %Y A356688 Cf. A256016, A356687. %Y A356688 Cf. A337001, A349901, A356673. %K A356688 nonn %O A356688 0,3 %A A356688 _Seiichi Manyama_, Aug 23 2022