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 A349860 #14 Dec 03 2021 09:52:57
%S A349860 0,1,1,-12,50,913,-35093,557048,15098348,-1975843727,103722820509,
%T A349860 -396969408196,-704487440688562,106081534307130081,
%U A349860 -7995154887120369801,-510404434212739199104,340061796037700870259064,-75820293495741408235957599,8142099722101269515604494937
%N A349860 Expansion of Sum_{k>=0} k * x^k/(1 + k^3 * x).
%F A349860 a(n) = Sum_{k=0..n} (-k^3)^(n-k) * k.
%t A349860 a[n_] := Sum[If[k == n - k == 0, 1, (-k^3)^(n-k)] * k, {k, 0, n}]; Array[a, 19, 0] (* _Amiram Eldar_, Dec 03 2021 *)
%o A349860 (PARI) a(n, s=1, t=3) = sum(k=0, n, (-k^t)^(n-k)*k^s);
%o A349860 (PARI) my(N=20, x='x+O('x^N)); concat(0, Vec(sum(k=0, N, k*x^k/(1+k^3*x))))
%Y A349860 Cf. A349859, A349861.
%K A349860 sign
%O A349860 0,4
%A A349860 _Seiichi Manyama_, Dec 02 2021