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 A081747 #3 Mar 30 2012 16:49:43 %S A081747 0,4,8,12,16,12,16,20,24,28,24,28,32,36,40,36,40,36,40,44,40,44,40,44, %T A081747 48,52,56,52,56,60,64,68,64,68,64,68,72,68,72,68,72,76,80,84,80,84,88, %U A081747 92,96,92,96,92,96,92,88,92,88,92,88,92,88,92,88,84,88,84,88 %N A081747 A081746(n) - n. %F A081747 Periodic with period 648. %Y A081747 Cf. A081746, A081748. %K A081747 nonn %O A081747 1,2 %A A081747 _N. J. A. Sloane_, Apr 08 2003