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 A349902 #14 Apr 12 2022 11:12:56 %S A349902 1,1,63,19172,16249870,29458152441,97813591721181,537081363012854224, %T A349902 4535464309375188976956,55796581668379082029481225, %U A349902 958824462567528346234944706075,22255431432328421226838750870120356,678866987929798923743810982299237129610 %N A349902 a(n) = Sum_{k=0..n} (-1)^(n-k) * k^(3*n). %F A349902 G.f.: Sum_{k>=0} (k^3 * x)^k/(1 + k^3 * x). %F A349902 a(n) ~ 1/(1 + exp(-3)) * n^(3*n). - _Vaclav Kotesovec_, Dec 10 2021 %t A349902 Join[{1},Table[Sum[(-1)^(n-k) k^(3n),{k,0,n}],{n,20}]] (* _Harvey P. Dale_, Apr 12 2022 *) %o A349902 (PARI) a(n) = sum(k=0, n, (-1)^(n-k)*k^(3*n)); %o A349902 (PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k^3*x)^k/(1+k^3*x))) %Y A349902 Cf. A120485, A349885, A349889, A349891. %K A349902 nonn %O A349902 0,3 %A A349902 _Seiichi Manyama_, Dec 05 2021