

A113109


Number of 5tournament sequences: a(n) gives the number of increasing sequences of n positive integers (t_1,t_2,...,t_n) such that t_1 = 2 and t_i = 2 (mod 4) and t_{i+1} <= 5*t_i for 1<i<n.


11



1, 2, 16, 440, 43600, 16698560, 26098464448, 172513149018752, 4938593053649344000, 622793203804403960906240, 350552003258337075784341271552, 890153650520295355798989668668129280
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OFFSET

0,2


COMMENTS

Equals column 0 of triangle A113108, which is the matrix square of triangle A113106, which satisfies the recurrence: A113106(n,k) = [A113106^5](n1,k1) + [A113106^5](n1,k).


LINKS

Table of n, a(n) for n=0..11.
M. Cook and M. Kleber, Tournament sequences and Meeussen sequences, Electronic J. Comb. 7 (2000), #R44.


EXAMPLE

The tree of 5tournament sequences of descendents
of a node labeled (2) begins:
[2]; generation 1: 2>[6,10]; generation 2:
6>[10,14,18,22,26,30], 10>[14,18,22,26,30,34,38,42,46,50]; ...
Then a(n) gives the number of nodes in generation n.
Also, a(n+1) = sum of labels of nodes in generation n.


PROG

(PARI) {a(n)=local(M=matrix(n+1, n+1)); for(r=1, n+1, for(c=1, r, M[r, c]=if(r==c, 1, if(c>1, (M^5)[r1, c1])+(M^5)[r1, c]))); return((M^2)[n+1, 1])}


CROSSREFS

Cf. A008934, A113077, A113078, A113079, A113085, A113089, A113096, A113098, A113100, A113107, A113111, A113113.
Sequence in context: A012682 A012678 A012146 * A223563 A140309 A201383
Adjacent sequences: A113106 A113107 A113108 * A113110 A113111 A113112


KEYWORD

nonn


AUTHOR

Paul D. Hanna, Oct 14 2005


STATUS

approved



