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 A264150 #15 Feb 09 2018 03:19:12
%S A264150 1,-1,1,1,-281,-5221,5459,91207079,-2650986803,-6171801683,
%T A264150 4283933145517,11963983648109,-208697624924077,-29320119130515566117,
%U A264150 2700231121460756431181,10084288256532215186381,-6782242429223267933535073,-51748587106835353426330148693
%N A264150 Numerators of SGGS((2*n+1)/2^(n+1)) where the rational numbers SGGS(n) are defined in A264148.
%C A264150 See A264148 for definitions and cross-references.
%H A264150 G. C. Greubel, <a href="/A264150/b264150.txt">Table of n, a(n) for n = 0..255</a>
%p A264150 h := proc(k) option remember; local j; `if`(k<=0, 1,
%p A264150 (h(k-1)/k-add((h(k-j)*h(j))/(j+1), j=1..k-1))/(1+1/(k+1))) end:
%p A264150 SGGS := n -> h(n)*doublefactorial(n-1):
%p A264150 A264150 := n -> numer(SGGS(2*n+1)/2^(n+1)): seq(A264150(n), n=0..17);
%t A264150 h[k_]:= h[k] = If[k <= 0, 1, (h[k - 1]/k - Sum[h[k - j]*h[j]/(j + 1), {j, 1, k - 1}])/(1 + 1/(k + 1))]; b[n_] := h[n]*Factorial2[n - 1]; Table[ Numerator[b[2*n + 1]/2^(n + 1)], {n,0,50}] (* _G. C. Greubel_, Feb 08 2018 *)
%Y A264150 Cf. A264148, denominators in A065973.
%K A264150 sign,frac
%O A264150 0,5
%A A264150 _Peter Luschny_, Nov 05 2015