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 A319175 #6 Sep 14 2018 14:29:23 %S A319175 1,1,4,36,416,6000,106542,2242093,54399424,1495318752,45938780750, %T A319175 1559858659359,58007497143180,2344682328265823,102352889947823998, %U A319175 4798930456964580045,240518006611511552896,12832137350594892322464,726108032647676403262710,43434461707962856186584307 %N A319175 a(n) = n! * [x^n] Product_{k>=1} (1 + x^k/k!)^n. %F A319175 a(n) = n! * [x^n] exp(n*Sum_{k>=1} Sum_{j>=1} (-1)^(k+1)*x^(j*k)/(k*(j!)^k)). %t A319175 Table[n! SeriesCoefficient[Product[(1 + x^k/k!)^n, {k, 1, n}], {x, 0, n}], {n, 0, 19}] %t A319175 Table[n! SeriesCoefficient[Exp[n Sum[Sum[(-1)^(k + 1) x^(j k)/(k (j!)^k), {j, 1, n}], {k, 1, n}]], {x, 0, n}], {n, 0, 19}] %Y A319175 Cf. A007837, A032312, A032314, A032315, A319174, A319177. %K A319175 nonn %O A319175 0,3 %A A319175 _Ilya Gutkovskiy_, Sep 12 2018