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 A081748 #3 Mar 30 2012 16:49:43 %S A081748 0,1,2,3,4,3,4,5,6,7,6,7,8,9,10,9,10,9,10,11,10,11,10,11,12,13,14,13, %T A081748 14,15,16,17,16,17,16,17,18,17,18,17,18,19,20,21,20,21,22,23,24,23,24, %U A081748 23,24,23,22,23,22,23,22,23,22,23,22,21,22,21,22,21,22,23,24 %N A081748 (A081746(n) - n)/4. %F A081748 Periodic with period 648. %Y A081748 Cf. A081746, A081747. %K A081748 nonn %O A081748 1,3 %A A081748 _N. J. A. Sloane_, Apr 08 2003