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 A091239 #7 Jul 28 2017 23:31:46 %S A091239 1,2,3,6,5,9,15,23,17,34,51,75,85,153,255,359,257,514,771,1275,1285, %T A091239 2313,3855,5911,4369,8738,13107,19275,21845,39321,65535 %N A091239 Smallest GF2X-Matula number i which encodes a tree of n nodes, i.e., for which A091238(i) = n. %H A091239 A. Karttunen, <a href="/A091247/a091247.scm.txt">Scheme-program for computing this sequence.</a> %Y A091239 Analogous to A005517. A091240 gives the largest i with number of nodes = n. Cf. A091238, A091241. %K A091239 nonn %O A091239 1,2 %A A091239 _Antti Karttunen_, Jan 03 2004