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 A052611 #22 Jan 31 2023 08:26:36
%S A052611 1,2,12,96,1056,14400,236160,4515840,98703360,2426941440,66305433600,
%T A052611 1992646656000,65328154214400,2320237766246400,88746105588940800,
%U A052611 3636883029491712000,158978387626426368000,7383729547341987840000
%N A052611 Expansion of e.g.f. 1/(1-2*x-2*x^2).
%H A052611 G. C. Greubel, <a href="/A052611/b052611.txt">Table of n, a(n) for n = 0..380</a>
%H A052611 INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=556">Encyclopedia of Combinatorial Structures 556</a>
%F A052611 E.g.f.: 1/(1 - 2*x - 2*x^2).
%F A052611 a(n) = 2^n * A080599(n).
%F A052611 a(n) = 2*n*a(n+1) + 2*n*(n-1)*a(n), a(0) = 1, a(1) = 2.
%F A052611 a(n) = (n!/6) * Sum_{p = RootOf(2*z^2+2*z-1)} (1+2*p)*p^(-n-1).
%F A052611 a(n) = n!*A002605(n+1). - _R. J. Mathar_, Nov 27 2011
%p A052611 spec := [S,{S=Sequence(Union(Z,Z,Prod(Z,Union(Z,Z))))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
%t A052611 With[{nn=20},CoefficientList[Series[1/(1-2x-2x^2),{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Apr 14 2015 *)
%t A052611 Table[n!*(-I*Sqrt[2])^(n)*ChebyshevU[n,I/Sqrt[2]], {n,0,40}] (* _G. C. Greubel_, Jan 31 2023 *)
%o A052611 (Magma) [n le 2 select n else 2*(n-1)*Self(n-1) + 2*(n-1)*(n-2)*Self(n-2): n in [1..41]]; // _G. C. Greubel_, Jan 31 2023
%o A052611 (SageMath)
%o A052611 A002605=BinaryRecurrenceSequence(2,2,0,1)
%o A052611 def A052611(n): return factorial(n)*A002605(n+1)
%o A052611 [A052611(n) for n in range(41)] # _G. C. Greubel_, Jan 31 2023
%Y A052611 Cf. A002605, A080599.
%K A052611 easy,nonn
%O A052611 0,2
%A A052611 encyclopedia(AT)pommard.inria.fr, Jan 25 2000