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 A004529 #18 Jun 20 2018 01:34:32
%S A004529 1,1,1,1,2,6,18,54,216,1080,5400,27000,162000,1134000,7938000,
%T A004529 55566000,444528000,4000752000,36006768000,324060912000,3240609120000,
%U A004529 35646700320000,392113703520000,4313250738720000
%N A004529 Ratios of successive terms are 1,1,1,2,3,3,3,4,5,5,5,6,...
%H A004529 Robert Israel, <a href="/A004529/b004529.txt">Table of n, a(n) for n = 0..506</a>
%F A004529 a(n) = Product_{j=0..n-1} (A180969(2,j+1) + A180969(2,j) + 1) = a(n-1) * (A180969(2,n-1) + A180969(2,n-2) + 1). - _Adriano Caroli_, Nov 27 2010
%F A004529 a(4*k+j) = 16^k * k! * Gamma(k+1/2)^3*(2*k+1)^j/Gamma(1/2)^3 for 0 <= j <= 3. - _Robert Israel_, Jun 19 2018
%p A004529 seq(seq(16^k * k! * GAMMA(k+1/2)^3*(2*k+1)^j/GAMMA(1/2)^3,j=0..3),k=0..10); # _Robert Israel_, Jun 19 2018
%K A004529 nonn
%O A004529 0,5
%A A004529 _N. J. A. Sloane_