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 A038157 #19 Dec 26 2021 14:37:49
%S A038157 0,0,0,6,36,200,1230,8652,69272,623520,6235290,68588300,823059732,
%T A038157 10699776672,149796873590,2246953104060,35951249665200,
%U A038157 611171244308672,11001082397556402,209020565553571980,4180411311071439980,87788637532500240000
%N A038157 a(n) = n! * Sum_{k=1..n-2} 1/k!.
%H A038157 Harvey P. Dale, <a href="/A038157/b038157.txt">Table of n, a(n) for n = 0..449</a>
%H A038157 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>
%F A038157 a(n) = floor(n!*exp(1)) - n - 1 - n! for n>1. - _Mark van Hoeij_, Oct 30 2011
%t A038157 a=1;Table[a=(a-n)*(n+1);Abs[a],{n,0,40}] (* _Vladimir Joseph Stephan Orlovsky_, Nov 20 2009 *)
%t A038157 Table[n!Sum[1/k!,{k,n-2}],{n,0,30}] (* _Harvey P. Dale_, Dec 26 2021 *)
%K A038157 nonn
%O A038157 0,4
%A A038157 _N. J. A. Sloane_