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 A056197 #10 May 12 2017 08:36:15
%S A056197 1,7,38,222,1464,10920,91440,851760,8749440,98340480,1201132800,
%T A056197 15846969600,224651750400,3406180377600,55009501747200,
%U A056197 942833219328000,17093919338496000,326876746420224000,6575237795782656000
%N A056197 Diagonal of A056151.
%F A056197 a(n)=(3n^2+3n+1)n!=((n+1)^3-n^3)n!=n!A003215(n). - _Paul Barry_, Apr 02 2003
%F A056197 E.g.f.: (1 + 4*x + x^2)/(1 - x)^3. - _Ilya Gutkovskiy_, May 12 2017
%t A056197 Table[(3n(n+1)+1)n!, {n, 0, 18}]
%Y A056197 Cf. A056151.
%K A056197 nonn,easy
%O A056197 0,2
%A A056197 _N. J. A. Sloane_, Aug 05 2000
%E A056197 More terms from _Wouter Meeussen_, Aug 05 2000