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 A052570 #18 Jun 03 2022 19:15:47
%S A052570 0,1,8,96,1536,30720,737280,20643840,660602880,23781703680,
%T A052570 951268147200,41855798476800,2009078326886400,104472072998092800,
%U A052570 5850436087893196800,351026165273591808000,22465674577509875712000
%N A052570 E.g.f.: x/(1-4*x).
%H A052570 INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=513">Encyclopedia of Combinatorial Structures 513</a>
%F A052570 Recurrence: {a(1)=1, a(0)=0, (-4-4*n)*a(n)+a(n+1)=0.}
%F A052570 4^(n-1)*n!=n!*A000302(n-1). for n >= 1.
%p A052570 spec := [S,{S=Prod(Z,Sequence(Union(Z,Z,Z,Z)))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
%t A052570 With[{nn=20},CoefficientList[Series[x/(1-4x),{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Jan 15 2017 *)
%Y A052570 A034177 is an essentially identical sequence. - _Philippe Deléham_, Sep 18 2008
%K A052570 easy,nonn
%O A052570 0,3
%A A052570 encyclopedia(AT)pommard.inria.fr, Jan 25 2000