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A318850
Number of rooted trees with n nodes such that no more than three isomorphic subtrees extend from the same node.
2
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
0,4
LINKS
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);
CROSSREFS
Column k=3 of A318757.
Sequence in context: A330269 A049075 A318797 * A052327 A059221 A193617
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Sep 04 2018
STATUS
approved