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 A335601 #7 Jun 15 2020 06:58:42 %S A335601 1,2,10,40,187,854,4074,19602,96035,475492,2380042,12015368,61130186, %T A335601 313081232,1612967974,8353387992,43464071199,227101948596, %U A335601 1191127734498,6268882232536,33096647906860,175236408484988,930271133498794,4950509216635406,26403755607304762,141119182968584618 %N A335601 The number of mixed trees with n nodes and n-2 arcs. %C A335601 Mixed trees are trees where a subset of the edges are directed (edges called arcs then). This is the first subdiagonal of A335362: n nodes implies trees with n-1 edges. If exactly one of these edges is not directed and the remaining n-2 edges are directed, the trees are counted here. %H A335601 <a href="/index/Tra#trees">Index entries for sequences related to trees</a> %F A335601 O.g.f. ( B(x)^2+B(x^2) )/2 where B(x) is the o.g.f. of A000151. %F A335601 a(n) = A335362(n,n-2). %Y A335601 Cf. A335362. %K A335601 nonn %O A335601 2,2 %A A335601 _R. J. Mathar_, Jun 15 2020