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 A353287 #9 Apr 10 2022 02:28:38
%S A353287 1,0,1,1,5,13,56,223,1056,5243,28401,163578,1003332,6506149,44464510,
%T A353287 319066188,2396942740,18800878491,153611297283,1304600660023,
%U A353287 11495292868763,104907727533628,990067627794487,9648859125705064,96978616443859923
%N A353287 a(n) = Sum_{k=0..floor(n/2)} k^k * Stirling2(n-k,k).
%F A353287 G.f.: Sum_{k>=0} k^k * x^(2*k)/Product_{j=1..k} (1 - j * x).
%o A353287 (PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=0, N, k^k*x^(2*k)/prod(j=1, k, 1-j*x)))
%o A353287 (PARI) a(n) = sum(k=0, n\2, k^k*stirling(n-k, k, 2));
%Y A353287 Cf. A097341, A097342, A171367, A353260, A353261.
%Y A353287 Cf. A353288.
%K A353287 nonn
%O A353287 0,5
%A A353287 _Seiichi Manyama_, Apr 09 2022