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 A147631 #18 Dec 21 2022 04:46:30
%S A147631 1,7,112,2800,95200,4093600,212867200,12984899200,908942944000,
%T A147631 71806492576000,6318971346688000,612940220628736000,
%U A147631 64971663386646016000,7471741289464291840000,926495919893572188160000,123223957345845101025280000,17497801943110004345589760000
%N A147631 9-factorial numbers (6).
%F A147631 a(n+1) = Sum_{k=0..n} A132393(n,k)*7^k*9^(n-k). - _Philippe Deléham_, Nov 09 2008
%F A147631 a(n) = (-2)^n*Sum_{k=0..n} (9/2)^k*s(n+1,n+1-k), where s(n,k) are the Stirling numbers of the first kind, A048994. - _Mircea Merca_, May 03 2012
%F A147631 Sum_{n>=1} 1/a(n) = 1 + (e/9^2)^(1/9)*(Gamma(7/9) - Gamma(7/9, 1/9)). - _Amiram Eldar_, Dec 21 2022
%t A147631 s=1;lst={s};Do[s+=n*s;AppendTo[lst,s],{n,6,2*5!,9}];lst
%Y A147631 Cf. A147630, A147629, A049211, A051232, A045756, A035012, A035013, A035017, A035018, A035020, A035022, A035023, A053116.
%Y A147631 Cf. A048994, A132393.
%K A147631 nonn
%O A147631 1,2
%A A147631 _Vladimir Joseph Stephan Orlovsky_, Nov 08 2008