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 A351514 #13 Feb 13 2022 06:33:18 %S A351514 1,12,136,1650,21904,318521,5051988,86910426,1612648066,32107793135, %T A351514 682724688430,15439016490989,369914992674530,9359103270641290, %U A351514 249292192469843244,6971850327184526783,204215496402215939638,6251233458455082035922 %N A351514 Expansion of e.g.f. (exp(exp(exp(exp(x)-1)-1)-1)-1)^2 / 2. %F A351514 a(n) = Sum_{k=1..n-1} binomial(n-1,k) * A000307(k) * A000307(n-k). %o A351514 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace((exp(exp(exp(exp(x)-1)-1)-1)-1)^2/2)) %o A351514 (PARI) T(n, k) = if(k==0, n<=1, sum(j=0, n, stirling(n, j, 2)*T(j, k-1))); %o A351514 a(n) = sum(k=1, n-1, binomial(n-1, k)*T(k, 4)*T(n-k, 4)); %Y A351514 Column 2 of A039812. %Y A351514 Cf. A000307, A000558, A351513, A351515. %K A351514 nonn %O A351514 2,2 %A A351514 _Seiichi Manyama_, Feb 12 2022