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 A120785 #2 Mar 31 2012 13:20:12 %S A120785 1,16,128,4096,32768,524288,4194304,268435456,2147483648,34359738368, %T A120785 274877906944,8796093022208,70368744177664,1125899906842624, %U A120785 9007199254740992,1152921504606846976 %N A120785 Denominators of partial sums of Catalan numbers scaled by powers of 1/16. %C A120785 Numerators are given under A120784. %C A120785 The listed numbers coincide with the denominators of sum(C(k)/(-16)^k,k=0..n). For the numerators see A120794. In general these denominators may be different. See e.g. A120783 versus A120793 and A120787 versus A120796. %C A120785 Also one fourth of denominators of partial sums for sqrt(2)+sqrt(3). See A121503 for the numerators. %F A120785 a(n)=denominator(r(n)), with the rationals r(n):=sum(C(k)/16^k,k=0..n) with C(k):=A000108(k) (Catalan numbers). %K A120785 nonn,easy,frac %O A120785 0,2 %A A120785 _Wolfdieter Lang_, Jul 20 2006