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 A072640 #2 May 01 2014 02:43:29 %S A072640 0,1,3,11,100,2090,415729,15670134831,2990945138477441778, %T A072640 28553369883190773267638351857949, %U A072640 22025764139998888788032314837232820672093881927968648914 %N A072640 Maximum position in A072660 where the value n occurs. %Y A072640 Binary width of each term: A072642. Cf. A072638, A072639, A072654. %K A072640 nonn %O A072640 0,3 %A A072640 _Antti Karttunen_, Jun 02 2002