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 A349885 #12 Dec 04 2021 08:55:33
%S A349885 1,1,3,-4,-218,4377,189549,-13317056,-283835940,117015022505,
%T A349885 -5604964950389,-1791024716075124,422751913131376674,
%U A349885 8850160172208790801,-30082452518043880807911,7173002090013176579439392,1556433498641034120823054072
%N A349885 Expansion of Sum_{k>=0} (k * x)^k/(1 + k^3 * x).
%F A349885 a(n) = Sum_{k=0..n} (-1)^(n-k) * k^(3*n-2*k).
%t A349885 a[n_] := Sum[If[k == 3*n - 2*k == 0, 1, (-1)^(n - k) * k^(3*n - 2*k)], {k, 0, n}]; Array[a, 17, 0] (* _Amiram Eldar_, Dec 04 2021 *)
%o A349885 (PARI) a(n, t=3) = sum(k=0, n, (-k^t)^(n-k)*k^k);
%o A349885 (PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k*x)^k/(1+k^3*x)))
%Y A349885 Cf. A120485, A349884.
%K A349885 sign
%O A349885 0,3
%A A349885 _Seiichi Manyama_, Dec 03 2021