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 A045631 #6 Mar 30 2012 18:35:35 %S A045631 1,1,2,6,20,70,243,889,3276,12276,46435,176869,677022,2602197, %T A045631 10033212,38787495,150286400,583434322,2268848988,8836447021, %U A045631 34461894010,134564992002,526025788992,2058359779051,8061905110548,31602659997975 %N A045631 Number of 2n-bead black-white reversible complementable strings with n black beads and fundamental period 2n. %F A045631 Moebius transform of A045723 (Christian Bower). %K A045631 nonn %O A045631 0,3 %A A045631 _David W. Wilson_