A113113 Number of 5-tournament sequences: a(n) gives the number of increasing sequences of n positive integers (t_1,t_2,...,t_n) such that t_1 = 4 and t_i = 4 (mod 4) and t_{i+1} <= 5*t_i for 1

1, 4, 56, 2704, 481376, 337587520, 978162377600, 12088945462984960, 651451173346940188160, 155573037664478034394215424, 166729581953452524706695313356800

Offset: 0

Author

Paul D. Hanna, Oct 14 2005

Keywords

• nonn

Comments

Column 0 of triangle A113112; A113112 is the matrix 4th power of triangle A113106, which satisfies the matrix recurrence: A113106(n,k) = [A113106^5](n-1,k-1) + [A113106^5](n-1,k). Also equals column 4 of square table A113103.

Examples

			The tree of 5-tournament sequences of descendents
of a node labeled (4) begins:
[4]; generation 1: 4->[8,12,16,20];
generation 2: 8->[12,16,20,24,28,32,36,40],
12->[16,20,24,28,32,36,40,44,48,52,56,60],
16->[20,24,28,32,36,40,44,48,52,56,60,64,68,72,76,80],
20->[24,28,32,36,40,44,48,52,56,60,64,68,72,76,80,84,88,92,96,100];
Then a(n) gives the number of nodes in generation n.
Also, a(n+1) = sum of labels of nodes in generation n.
		

Links

• T. D. Noe, Table of n, a(n) for n=0..30
• M. Cook and M. Kleber, Tournament sequences and Meeussen sequences, Electronic J. Comb. 7 (2000), #R44.

Crossrefs

Cf. A008934, A113077, A113078, A113079, A113085, A113089, A113096, A113098, A113100, A113107, A113109, A113111.

Programs

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)[r-1,c-1])+(M^5)[r-1,c]))); return((M^4)[n+1,1])}