

A124501


Number of 123456 trees with n edges and with thinning limbs. A 123456 tree is an ordered tree with vertices of outdegree at most 6. A rooted tree with thinning limbs is such that if a node has k children, all its children have at most k children.


3



1, 1, 2, 4, 10, 25, 68, 186, 522, 1479, 4246, 12289, 35872, 105411, 311662, 926270, 2765778, 8292296, 24953437, 75338686, 228140842, 692733127, 2108652750, 6433255041, 19668210742, 60247367313, 184879648441, 568281131800
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OFFSET

0,3


COMMENTS

The sequences corresponding to k=2 (A090344), k=3 (A124497), k=4 (A124499), k=5 (A124500), k=6 (this A124501), etc. approach sequence A124344, corresponding to ordered trees with thinning limbs.


LINKS

Table of n, a(n) for n=0..27.


FORMULA

In general, if M[k](z) is the g.f. of the 12...k trees with thinning limbs and C[k](z)=1+z*{C[k](z)}^k is the g.f. of the kary trees, then M[k](z)=M[k1](z)*C[k](M[k1]^(k1)*z^k), M[1](z)=1/(1z).


PROG

(PARI) {a(n)=local(k=6, M=1+x*O(x^n)); for(i=1, k, M=M*sum(j=0, n, binomial(i*j, j)/((i1)*j+1)*(x^i*M^(i1))^j)); polcoeff(M, n)} \\ Paul D. Hanna


CROSSREFS

Cf. A090344, A124497, A124499, A124500, A124344.
Sequence in context: A124500 A220872 A317876 * A124344 A049125 A191768
Adjacent sequences: A124498 A124499 A124500 * A124502 A124503 A124504


KEYWORD

nonn


AUTHOR

Emeric Deutsch and Louis Shapiro, Nov 06 2006


STATUS

approved



