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 A056543 #23 Jul 02 2025 16:02:00
%S A056543 1,1,2,7,34,203,1420,11359,102230,1022299,11245288,134943455,
%T A056543 1754264914,24559708795,368395631924,5894330110783,100203611883310,
%U A056543 1803665013899579,34269635264092000,685392705281839999,14393246810918639978,316651429840210079515,7282982886324831828844
%N A056543 a(n) = n*a(n-1) - 1 with a(1)=1.
%C A056543 If s(n) is a sequence defined by s(0)=x, s(n)=(n+1)*s(n-1)+k, n>0, then s(n) = n!*x +(n! - a(n+1))*k. - _Gary Detlefs_, Jun 10 2010
%H A056543 Harvey P. Dale, <a href="/A056543/b056543.txt">Table of n, a(n) for n = 1..450</a>
%F A056543 a(n) = ceiling((3-e)*n!) = n! - A056542(n) = 2*n! - A002627(n) = 3*n! - A000522(n).
%e A056543 a(4) = 4*a(3) - 1 = 4*2 - 1 = 7.
%t A056543 nxt[{n_,a_}]:={n+1,a(n+1)-1}; NestList[nxt,{1,1},30][[All,2]] (* _Harvey P. Dale_, Dec 31 2022 *)
%K A056543 easy,nonn
%O A056543 1,3
%A A056543 _Henry Bottomley_, Jun 20 2000
%E A056543 More terms from _James Sellers_, Jul 04 2000