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 A355290 #15 Mar 13 2023 15:53:06
%S A355290 1,1,1,0,-3,-2,23,17,-333,86,6941,-17025,-160267,1082864,2273807,
%T A355290 -56742606,152154285,2293098332,-22007462809,-15179437171,
%U A355290 1671107690083,-10716783889040,-58404948615167,1439391012463810,-6701658223127029,-88340107011433060
%N A355290 a(n) = Sum_{k=0..n} (-1)^(n-k) * Stirling2(n,k) * Catalan(k).
%F A355290 G.f.: Sum_{k>=0} Catalan(k) * x^k / Product_{j=1..k} (1 + j*x).
%p A355290 A355290 := proc(n)
%p A355290 add((-1)^(n-k)*stirling2(n,k)*A000108(k),k=0..n) ;
%p A355290 end proc:
%p A355290 seq(A355290(n),n=0..70) ; # _R. J. Mathar_, Mar 13 2023
%o A355290 (PARI) a(n) = sum(k=0, n,(-1)^(n-k)*stirling(n, k, 2)*binomial(2*k, k)/(k+1));
%o A355290 (PARI) my(N=30, x='x+O('x^N)); Vec(sum(k=0, N, binomial(2*k, k)/(k+1)*x^k/prod(j=1, k, 1+j*x)))
%Y A355290 Cf. A000108, A006531, A064856, A086662, A086672.
%K A355290 sign
%O A355290 0,5
%A A355290 _Seiichi Manyama_, Jun 27 2022