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 A277001 #14 Sep 09 2018 09:40:07
%S A277001 1,24,5760,2903040,1393459200,367873228800,24103053950976000,
%T A277001 115694658964684800,9440684171518279680000,
%U A277001 271211974879377138647040000,3579998068407778230140928000000,1976158933761093583037792256000000,258955866680053703121272297226240000000
%N A277001 Denominators of an asymptotic series for the Gamma function (even power series).
%C A277001 For formulas and references see A277000 which is the main entry for this rational sequence.
%e A277001 The underlying rational sequence starts:
%e A277001 1, 0, -1/24, 0, 19/5760, 0, -2561/2903040, 0, 874831/1393459200, 0, ...
%p A277001 b := n -> CompleteBellB(n,0,seq((k-2)!*bernoulli(k,1/2),k=2..n))/n!:
%p A277001 A277001 := n -> denom(b(2*n)): seq(A277001(n), n=0..12);
%t A277001 CompleteBellB[n_, zz_] := Sum[BellY[n, k, zz[[1 ;; n-k+1]]], {k, 1, n}];
%t A277001 b[n_] := CompleteBellB[n, Join[{0}, Table[(k-2)! BernoulliB[k, 1/2], {k, 2, n}]]]/n!;
%t A277001 a[n_] := Denominator[b[2n]];
%t A277001 Table[a[n], {n, 0, 12}] (* _Jean-François Alcover_, Sep 09 2018 *)
%Y A277001 Cf. A277000 (numerators), A277002/A277003 (odd power series).
%K A277001 nonn,frac
%O A277001 0,2
%A A277001 _Peter Luschny_, Sep 25 2016