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 A305467 #12 Jun 03 2018 03:51:36
%S A305467 1,1,7,150,5857,363045,32817311,4078256168,667231014401,
%T A305467 139047475691385,35961972186044999,11303290914120251574,
%U A305467 4243674498966718214113,1875719852330658989518045,964140893268009386931042943,570249392860305817156465883040
%N A305467 a(n) = Sum_{k=0..floor(n/2)} ((n-k)!/k!)*binomial(n-k,k)*n^(n-2*k)*(-1)^k.
%H A305467 Seiichi Manyama, <a href="/A305467/b305467.txt">Table of n, a(n) for n = 0..232</a>
%F A305467 a(n) ~ n! * n^n. - _Vaclav Kotesovec_, Jun 03 2018
%o A305467 (PARI) {a(n) = sum(k=0, n/2, ((n-k)!/k!)*binomial(n-k, k)*n^(n-2*k)*(-1)^k)}
%Y A305467 Main diagonal of A305466.
%Y A305467 Cf. A305465.
%K A305467 nonn
%O A305467 0,3
%A A305467 _Seiichi Manyama_, Jun 02 2018