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 A136797 #13 Nov 17 2024 11:49:27
%S A136797 2,8,96,2048,64000,2654208,137682944,8589934592,626913312768,
%T A136797 52428800000000,4944974716076032,519400496868360192,
%U A136797 60134924074807721984,7609328110443312447488,1044855521280000000000000,154742504910672534362390528,24588026787102364507838611456
%N A136797 Number of labeled marked trees with n nodes.
%C A136797 A marked tree is a tree where each node and edge is marked as + or -.
%D A136797 F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, p. 293 (4.1.60).
%H A136797 Andrew Howroyd, <a href="/A136797/b136797.txt">Table of n, a(n) for n = 1..200</a>
%H A136797 <a href="/index/Tra#trees">Index entries for sequences related to trees</a>
%F A136797 a(n) = A136796(n)/n.
%F A136797 a(n) = 2^(2*n-1) * n^(n-2). - _Andrew Howroyd_, Feb 02 2020
%t A136797 Table[2^(2n-1) n^(n-2),{n,20}] (* _Harvey P. Dale_, Nov 17 2024 *)
%o A136797 (PARI) a(n) = {2^(2*n-1) * n^(n-2)} \\ _Andrew Howroyd_, Feb 02 2020
%Y A136797 Cf. A136796.
%K A136797 nonn
%O A136797 1,1
%A A136797 _Christian G. Bower_, Jan 21 2008
%E A136797 Terms a(15) and beyond from _Andrew Howroyd_, Feb 02 2020