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 A356687 #17 Aug 24 2022 12:09:11
%S A356687 1,1,18,927,94876,16251045,4210190766,1543550310211,764096247603480,
%T A356687 493254380867214249,404269328278061434810,411862088865696890314311,
%U A356687 512690851568229926690616948,768775988931240685277619894157
%N A356687 a(n) = n! * Sum_{k=0..n} k^(2*n)/k!.
%H A356687 Seiichi Manyama, <a href="/A356687/b356687.txt">Table of n, a(n) for n = 0..196</a>
%F A356687 E.g.f.: Sum_{k>=0} (k^2 * x)^k / (k! * (1 - k^2 * x)).
%t A356687 a[n_] := n! * Sum[k^(2*n)/k!, {k, 0, n}]; a[0] = 1; Array[a, 14, 0] (* _Amiram Eldar_, Aug 23 2022 *)
%o A356687 (PARI) a(n) = n!*sum(k=0, n, k^(2*n)/k!);
%o A356687 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(sum(k=0, N, (k^2*x)^k/(k!*(1-k^2*x)))))
%Y A356687 Cf. A256016, A356688.
%Y A356687 Cf. A030297, A249459, A356672.
%K A356687 nonn
%O A356687 0,3
%A A356687 _Seiichi Manyama_, Aug 23 2022