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 A382676 #12 Apr 04 2025 06:31:29
%S A382676 1,4,52,1372,60316,3964684,363503932,44280657292,6913081723516,
%T A382676 1345238707327564,319137578070718012,90648956570718822412,
%U A382676 30369040605677566161916,11848724306426305222109644,5325560174867275152102351292,2731649923185995549312271694732
%N A382676 a(n) = Sum_{k=0..n} (k!)^2 * binomial(k+2,2) * Stirling2(n+1,k+1)^2.
%F A382676 a(n) = (n!)^2 * [(x*y)^n] exp(x+y) / (exp(x) + exp(y) - exp(x+y))^3.
%o A382676 (PARI) a(n) = sum(k=0, n, k!^2*binomial(k+2, 2)*stirling(n+1, k+1, 2)^2);
%Y A382676 Main diagonal of A382673.
%Y A382676 Cf. A048163, A092552, A382678.
%K A382676 nonn
%O A382676 0,2
%A A382676 _Seiichi Manyama_, Apr 03 2025