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 A066968 #18 Jun 18 2018 03:14:51
%S A066968 15,6552,5026560,15590400,4561108992,244729774080,15293220913152,
%T A066968 6027885936640,2292288470384640,143113842220597248,
%U A066968 2278611404728565760,39351244081172840448,3515953192213728460800,2551413037895138672640
%N A066968 Denominators of b(n) = (1/16)^n*(4/(8*n+1) - 2/(8*n+4) - 1/(8*n+5) - 1/(8*n+6)).
%H A066968 G. C. Greubel, <a href="/A066968/b066968.txt">Table of n, a(n) for n = 0..815</a>
%H A066968 B. Gourevitch, <a href="http://www.pi314.net">L'univers de Pi</a>
%F A066968 Sum_{k>=0} b(k) = Pi.
%t A066968 Denominator[Table[1/16^n (4/(8n+1)-2/(8n+4)-1/(8n+5)-1/(8n+6)),{n,0,20}]] (* _Harvey P. Dale_, Jul 16 2014 *)
%o A066968 (PARI) a(n)=denominator(1/16^n*(4/(8*n+1)-2/(8*n+4)-1/(8*n+5)-1/(8*n+6)))
%Y A066968 Cf. A048581.
%K A066968 easy,frac,nonn
%O A066968 0,1
%A A066968 _Benoit Cloitre_, Aug 13 2002