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 A072781 #2 May 01 2014 02:47:42 %S A072781 0,1,0,2,2,1,2,3,2,0,3,4,4,3,1,3,4,5,4,2,0,4,5,6,6,5,3,1,4,5,6,7,6,4, %T A072781 2,0,5,6,7,8,8,7,5,3,1,5,6,7,8,9,8,6,4,2,0,6,7,8,9,10,10,9,7,5,3,1,6, %U A072781 7,8,9,10,11,10,8,6,4,2,0,7,8,9,10,11,12,12,11,9,7,5,3,1,7,8,9,10,11,12,13 %N A072781 X-projection of the tabular N X N -> N bijection A072735. %o A072781 (Scheme) (define (A072781 n) (A025581 (A072734 n))) %Y A072781 The Y-projection is A072782. Composition of A025581 & A072734. A072785(n) = A072781(n)-A072738(n). %K A072781 nonn,tabl %O A072781 0,4 %A A072781 _Antti Karttunen_, Jun 12 2002