A318851 Number of rooted trees with n nodes such that no more than four isomorphic subtrees extend from the same node.

0, 1, 1, 2, 4, 9, 19, 46, 110, 273, 684, 1746, 4503, 11758, 30943, 82118, 219341, 589485, 1592447, 4322433, 11781565, 32235688, 88503331, 243750729, 673246211, 1864422803, 5175655984, 14399854855, 40146793094, 112145140408, 313826549732, 879685174894

Offset

0,4

Links

Alois P. Heinz, Table of n, a(n) for n = 0..2143

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(4, 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);

Crossrefs

Column k=4 of A318757.

Sequence in context: A372102 A134964 A318798 * A052328 A133228 A036717

Adjacent sequences: A318848 A318849 A318850 * A318852 A318853 A318854

Keyword

nonn

Author

Alois P. Heinz, Sep 04 2018

Status

approved