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A245053
Number of hybrid 10-ary trees with n internal nodes.
2
1, 2, 39, 1103, 36650, 1333156, 51392991, 2062946770, 85311756697, 3609589528430, 155513170273468, 6799151325525095, 300899538364069838, 13453346159391591392, 606776046327452415295, 27573839101542183831805, 1261298294289947726165466, 58029238642196850552991302
OFFSET
0,2
LINKS
SeoungJi Hong and SeungKyung Park, Hybrid d-ary trees and their generalization, Bull. Korean Math. Soc. 51 (2014), No. 1, pp. 229-235
FORMULA
a(n) = 1/(9*n+1) * Sum_{i=0..n} C(9*n+i,i)*C(9*n+i+1,n-i).
a(n) = [x^n] ((1+x)/(1-x-x^2))^(9*n+1) / (9*n+1).
G.f. satisfies: A(x) = (1+x*A(x)^9) * (1+x*A(x)^10).
MAPLE
a:= n-> add(binomial(9*n+i, i)*binomial(9*n+i+1, n-i), i=0..n)/(9*n+1):
seq(a(n), n=0..20);
CROSSREFS
Column k=10 of A245049.
Sequence in context: A319520 A209632 A266863 * A352021 A177773 A274574
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jul 10 2014
STATUS
approved