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 A052588 #19 Jul 22 2024 17:16:09
%S A052588 1,0,2,12,48,600,5760,65520,967680,14515200,250387200,4790016000,
%T A052588 98195328000,2204365363200,53178757632000,1371750412032000,
%U A052588 37828404117504000,1107254963662848000,34316723062702080000
%N A052588 Expansion of e..g.f.: (1-x)/(1-x-x^2-x^3+x^4).
%H A052588 INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=533">Encyclopedia of Combinatorial Structures 533</a>
%F A052588 E.g.f.: -(-1+x)/(1-x-x^3+x^4-x^2)
%F A052588 Recurrence: {a(1)=0, a(0)=1, a(2)=2, a(3)=12, (n^4+35*n^2+50*n+24+10*n^3)*a(n) +(-n^3-9*n^2-26*n-24)*a(n+1) +(-n^2-7*n-12)*a(n+2) +(-n-4)*a(n+3) +a(n+4)=0}
%F A052588 Sum(-1/39*(-2-11*_alpha+4*_alpha^2+_alpha^3)*_alpha^(-1-n), _alpha=RootOf(1-_Z-_Z^3+_Z^4-_Z^2))*n!
%F A052588 a(n) = n!*A052527(n). - _R. J. Mathar_
%p A052588 spec := [S,{S=Sequence(Prod(Z,Z,Union(Z,Sequence(Z))))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
%t A052588 With[{nn=20},CoefficientList[Series[(1-x)/(1-x-x^2-x^3+x^4),{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Jul 22 2024 *)
%K A052588 easy,nonn
%O A052588 0,3
%A A052588 encyclopedia(AT)pommard.inria.fr, Jan 25 2000
%E A052588 Definition clarified by _Harvey P. Dale_, Jul 22 2024