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 A136795 #7 Feb 18 2018 20:14:59 %S A136795 2,6,20,112,662,4596,34032,268280,2201634,18679362,162611904, %T A136795 1446148032,13090979394,120303384120,1119971272340,10544483234056, %U A136795 100261309326082,961692928106614,9296529143261548,90497666895840376 %N A136795 Number of unlabeled marked trees with n nodes. %C A136795 A marked tree is a tree where each node and edge is marked as + or -. %D A136795 F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, p. 293 (4.1.60). %H A136795 <a href="/index/Tra#trees">Index entries for sequences related to trees</a> %F A136795 G.f.: B(x) - B(x)^2 + B(x^2) where B(x) is g.f. of A136794. %Y A136795 Cf. A136794 (rooted tree version), A136797 (labeled version). %K A136795 nonn %O A136795 1,1 %A A136795 _Christian G. Bower_, Jan 21 2008