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Number of rooted trees with n nodes such that no more than three subtrees of the same size extend from the same node.
2

%I #6 Sep 03 2018 20:55:01

%S 0,1,1,2,4,8,18,43,102,250,623,1579,4042,10470,27350,72034,190956,

%T 509259,1365271,3677522,9947145,27007988,73582758,201103314,551190098,

%U 1514683667,4172470962,11519509386,31869341642,88337853393,245301368188,682307613945

%N Number of rooted trees with n nodes such that no more than three subtrees of the same size extend from the same node.

%H Alois P. Heinz, <a href="/A318797/b318797.txt">Table of n, a(n) for n = 0..2158</a>

%p g:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0, add(

%p binomial(g((i-1)$2)+j-1, j)*g(n-i*j, i-1), j=0..min(3, n/i))))

%p end:

%p a:= n-> g((n-1)$2):

%p seq(a(n), n=0..40);

%Y Column k=3 of A318753.

%K nonn

%O 0,4

%A _Alois P. Heinz_, Sep 03 2018