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 A020945 #3 Mar 30 2012 18:55:50 %S A020945 1,1,0,2,2,1,1,2,1,4,3,3,0,2,2,3,1,3,2,5,3,7,4,6,2,3,1,2,1,4,3,5,2,4, %T A020945 2,4,2,5,3,7,4,8,4,10,6,11,5,10,5,8,3,5,2,4,2,3,1,3,2,5,3,7,4,8,4,7,3, %U A020945 6,3,6,3,6,3,6,3,7,4,8,4,10,6,11,5,12,7,12,5,14,9,16,7,17,10,16 %N A020945 a(2n+1) = |a(2n) - a(2n-1)|, a(2n) = a(n) + a(n-1). %Y A020945 Cf. A020947-A020950. %K A020945 nonn %O A020945 1,4 %A A020945 _Clark Kimberling_