A318850 Number of rooted trees with n nodes such that no more than three isomorphic subtrees extend from the same node.

0, 1, 1, 2, 4, 8, 18, 43, 102, 250, 623, 1579, 4042, 10473, 27356, 72049, 190991, 509384, 1365586, 3678369, 9949452, 27014550, 73600711, 201153143, 551329088, 1515078957, 4173575232, 11522620375, 31878127954, 88362886345, 245372235144, 682508792835

Offset: 0

Author

Alois P. Heinz, Sep 04 2018

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..2158

Crossrefs

Column k=3 of A318757.

Programs

Maple

h:= proc(n, m, t) option remember; `if`(m=0, binomial(n+t, t),
      `if`(n=0, 0, add(h(n-1, m-j, t+1), j=1..min(3, m))))
    end:
b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
      add(b(n-i*j, i-1)*h(a(i), j, 0), j=0..n/i)))
    end:
a:= n-> `if`(n<2, n, b(n-1$2)):
seq(a(n), n=0..35);