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 A011266 #38 Mar 10 2022 21:32:33
%S A011266 1,1,4,48,1536,122880,23592960,10569646080,10823317585920,
%T A011266 24936923717959680,127677049435953561600,1438154284846580917862400,
%U A011266 35344079704389572637386342400,1882001556099335963795547960115200,215842994465920643015783804449692057600
%N A011266 a(n) = 2^(n*(n-1)/2)*n!.
%C A011266 Let A = the sum of the n-th powers of the first 2^{n-1} terms of A001969, and similarly let B = the sum of the n-th powers of the first 2^{n-1} terms of A000069. Then a(n) = |A-B|. - _Jeffrey Shallit_, Nov 29 2019
%H A011266 Alois P. Heinz, <a href="/A011266/b011266.txt">Table of n, a(n) for n = 0..77</a>
%H A011266 Richard P. Stanley, <a href="http://dx.doi.org/10.1016/0012-365X(73)90108-8">Acyclic Orientations of Graphs</a>, Discrete Mathematics, 5 (1973), pages 171-178, doi:10.1016/0012-365X(73)90108-8.
%F A011266 From _Mehdi Naima_, Mar 09 2022: (Start)
%F A011266 a(n) = a(n-1)*n*2^(n-1), a(0) = 1.
%F A011266 G.f. satisfies A(x) = 1 + x * (x * A(2*x))'. (End)
%p A011266 a:= n-> 2^(n*(n-1)/2)*n!:
%p A011266 seq(a(n), n=0..15); # _Alois P. Heinz_, Apr 21 2020
%t A011266 Table[2^((n(n-1))/2) n!,{n,0,20}] (* _Harvey P. Dale_, Dec 16 2012 *)
%o A011266 (PARI) a(n) = n! << binomial(n,2); \\ _Kevin Ryde_, Mar 10 2022
%Y A011266 Main diagonal of A046860.
%Y A011266 Cf. A000069, A001969.
%K A011266 nonn
%O A011266 0,3
%A A011266 _N. J. A. Sloane_