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 A036661 #16 Jun 12 2022 06:42:52 %S A036661 1,1,2,4,8,15,32,66,142,306,672,1483,3316,7446,16859,38353,87735, %T A036661 201510,464801,1075744,2498053,5817576,13585231,31801732,74615404, %U A036661 175433624,413281276,975355639,2305763635,5459480822,12945857671 %N A036661 Number of n-node rooted labeled trees with deg <= 4 at root and outdegree <= 2 elsewhere. %H A036661 <a href="/index/Ro#rooted">Index entries for sequences related to rooted trees</a> %H A036661 <a href="/index/Tra#trees">Index entries for sequences related to trees</a> %F A036661 G.f.: A(x) = x*cycle_index(S4, f), where f = A001190(x)/x. %Y A036661 Cf. A000671, A001190. %K A036661 nonn,easy %O A036661 0,3 %A A036661 _N. J. A. Sloane_