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 A094547 #5 Mar 30 2012 17:38:04 %S A094547 1,3,12,45,180,708,2832,11283,45132,180348,721392,2884860,11539440, %T A094547 46154928,184619712,738467565,2953870260,11815435908,47261743632, %U A094547 189046794180,756187176720,3024747985488,12098991941952,48395964882948 %N A094547 A019309(n)/4 for n >= 1. %F A094547 a(2n+1) = 4*a(2n); a(2n) = 4*a(2n-1)-a(n). - _David Wasserman_, May 22 2007 %K A094547 nonn,easy %O A094547 1,2 %A A094547 _N. J. A. Sloane_, Jun 06 2004 %E A094547 More terms from _David Wasserman_, May 22 2007