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 A052578 #33 Sep 08 2022 08:44:59
%S A052578 0,4,8,24,96,480,2880,20160,161280,1451520,14515200,159667200,
%T A052578 1916006400,24908083200,348713164800,5230697472000,83691159552000,
%U A052578 1422749712384000,25609494822912000,486580401635328000,9731608032706560000,204363768686837760000
%N A052578 a(0) = 0, a(n) = 4*n! for n > 0.
%H A052578 Vincenzo Librandi, <a href="/A052578/b052578.txt">Table of n, a(n) for n = 0..447</a>
%H A052578 Luis Manuel Rivera, <a href="http://arxiv.org/abs/1406.3081">Integer sequences and k-commuting permutations</a>, arXiv preprint arXiv:1406.3081 [math.CO], 2014-2015.
%H A052578 INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=522">Encyclopedia of Combinatorial Structures 522</a>
%F A052578 E.g.f.: -4*x/(-1+x)
%F A052578 Recurrence: {a(0)=0, (-1-n)*a(n)+a(n+1), a(1)=4}
%p A052578 spec := [S,{S=Prod(Union(Z,Z,Z,Z),Sequence(Z))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
%t A052578 Join[{0},4Range[25]!] (* _Harvey P. Dale_, Mar 12 2011 *)
%o A052578 (PARI) a(n)=if(n,4*n!,0) \\ _Charles R Greathouse IV_, Nov 20 2011
%o A052578 (Magma) [0] cat [4*Factorial(n): n in [1..25]]; // _Vincenzo Librandi_, Feb 13 2018
%Y A052578 Cf. A000142, A052849 (k=2), A052560 (k=3).
%K A052578 easy,nonn
%O A052578 0,2
%A A052578 encyclopedia(AT)pommard.inria.fr, Jan 25 2000