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 A192552 #9 Jul 05 2021 07:13:17
%S A192552 1,1,3,25,387,9481,336723,16340185,1038177507,83616187561,
%T A192552 8323660051443,1003415542660345,144043181112445827,
%U A192552 24279259683302736841,4747993384270354742163,1066206704980940216628505,272480888391150986151565347
%N A192552 a(n) = sum(stirling2(n,k)*(-1)^(n-k)*k!^2,k=0..n).
%F A192552 O.g.f.: Sum_{n>=0} n!^2 * x^n / Product_{k=0..n} (1 + k*x). [From Paul D. Hanna, Jul 20 2011]
%F A192552 a(n) ~ exp(-1/2) * n!^2. - _Vaclav Kotesovec_, Jul 05 2021
%t A192552 Table[Sum[StirlingS2[n,k](-1)^(n-k)k!^2,{k,0,n}],{n,0,100}]
%o A192552 (Maxima) makelist(sum(stirling2(n,k)*(-1)^(n-k)*k!^2,k,0,n),n,0,24);
%o A192552 (PARI) {a(n)=polcoeff(sum(m=0, n, m!^2*x^m/prod(k=1, m, 1+k*x+x*O(x^n))), n)} /* Paul D. Hanna, Jul 20 2011 */
%K A192552 nonn
%O A192552 0,3
%A A192552 _Emanuele Munarini_, Jul 04 2011