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 A081745 #3 Mar 30 2012 16:49:43 %S A081745 1,-2,2,6,3,7,11,8,12,9,13,17,14,18,22,19,23,20,17,21,18,22,26,23,27, %T A081745 31,28,32,29,33,37,34,38,42,39,36,33,30,27,24,21,25,29,26,30,34,31,35, %U A081745 32,36,40,37,41,45,42,46,43,40,44,41,45,42,39,36,40,37,34,31 %N A081745 a(n) = A080901(n) - n. %F A081745 Periodic with period 168. %K A081745 sign %O A081745 1,2 %A A081745 _N. J. A. Sloane_, Apr 08 2003