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 A063682 #4 May 10 2013 12:44:50 %S A063682 0,1,3,13,52,229,1024,4749,22454,108299,529896,2625903,13148268, %T A063682 66428383,338197609,1733399552,8936746984,46315049443,241146306914, %U A063682 1260805087503,6616786338256,34843842405490,184057255372576 %N A063682 Number of 2-trees rooted at an asymmetric end-edge. %D A063682 F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 75, Eq. (3.5.4). %Y A063682 Cf. A058870, A058866, A054581. %K A063682 nonn %O A063682 1,3 %A A063682 _Vladeta Jovovic_, Aug 22 2001