%I #11 Jun 09 2020 09:21:57
%S 4,17,66,221,688,2034,5788,15998,43192,114496,298712,769340,1959064,
%T 4940761,12354210,30660947,75583868,185208833,451356846,1094522547,
%U 2642121008,6351335083,15208854510,36288478177,86295204732,204571273167,483532711338,1139738858221
%N The number of oriented star-like and star trees with n arcs.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Starlike_tree">Starlike Tree</a>
%H <a href="/index/Tra#trees">Index entries for sequences related to trees</a>
%F a(n) = A034899(n) -2^(n+1) = Sum_{k>=3} A209406(n,k).
%e a(6)=221 counts 132 oriented star-like trees with 3 rays and 6 arcs, 62 with 4 rays and 6 arcs, 20 with 5 rays and 6 arcs, and 7 star trees. In the illustrations in A000238 [Mathar] this is the same as 48 (shape 2) + 64 (shape 3) + 20 (shape 4) +32 (shape 7) + 30 (shape 8) +20 (shape 10) + 7 (shape 11).
%Y Cf. A000238 (oriented trees), A051437 (linear oriented trees), A209406 (star-like oriented by number of arcs and rays), A004250 (undirected edges).
%K nonn
%O 3,1
%A _R. J. Mathar_, Jun 09 2020