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 A157217 #8 Mar 30 2012 18:52:03 %S A157217 1,2,3,6,9,10,19,28,47,51,98,122,220,221,441,444,885,886,1771,1780, %T A157217 3551,3555,7106,7173,14279,14280,28559,28562,57121,57122,114243, %U A157217 114252,228495,228499,456994,457018,914012,914013,1828025,1828028,3656053,3656054,7312107,7312116 %N A157217 Mix A091411 and its differences. %C A157217 First differences: 1, 1, 3, 3, 1, 9, 9, 19, 4, 47, .... %F A157217 a(2n) = A091441(n+1). a(2n-1) = A091441(n+1)-A091441(n). %K A157217 nonn,less %O A157217 0,2 %A A157217 _Paul Curtz_, Feb 25 2009