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A303271
Number of ordered rooted trees with n non-root nodes such that the maximal outdegree equals three.
2
1, 4, 15, 53, 182, 616, 2070, 6930, 23166, 77429, 258973, 867230, 2908633, 9772556, 32896088, 110949072, 374934201, 1269505482, 4306750577, 14638006449, 49843505965, 170021694271, 580954640775, 1988357053020, 6816047416230, 23400699072231, 80455436055699
OFFSET
3,2
LINKS
FORMULA
a(n) = A036765(n) - A001006(n).
MAPLE
b:= proc(u, o, k) option remember; `if`(u+o=0, 1,
add(b(u-j, o+j-1, k), j=1..min(1, u))+
add(b(u+j-1, o-j, k), j=1..min(k, o)))
end:
a:= n-> b(0, n, 3)-b(0, n, 2):
seq(a(n), n=3..35);
CROSSREFS
Column k=3 of A203717.
Sequence in context: A171309 A210781 A367818 * A289802 A071719 A370034
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Apr 20 2018
STATUS
approved