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 A274326 #8 Jun 18 2016 11:15:22 %S A274326 0,0,1,2,11,40 %N A274326 Number of distinct irregular n-gon flexagons. %D A274326 Les Pook, Flexagons inside out, Cambridge University Press, 2003, p. 84. %e A274326 a(6) = 11, because there are 11 distinct irregular hexaflexagons. %Y A274326 Cf. A001683. %K A274326 nonn,hard,more %O A274326 2,4 %A A274326 _Christian Schroeder_, Jun 18 2016