A113096 Number of 4-tournament sequences: a(n) gives the number of increasing sequences of n positive integers (t_1,t_2,...,t_n) such that t_1 = 1 and t_i = 1 (mod 3) and t_{i+1} <= 4*t_i for 1

1, 1, 4, 46, 1504, 146821, 45236404, 46002427696, 159443238441379, 1926751765436372746, 82540801108546193896804, 12696517688186899788062326096, 7084402815778394692932546017050054

Offset: 0

Author

Paul D. Hanna, Oct 14 2005

Keywords

• nonn

Comments

Equals column 0 of triangle A113095, which satisfies: A113095(n,k) = [A113095^4](n-1,k-1) + [A113095^4](n-1,k).

Examples

			The tree of 4-tournament sequences of descendents
of a node labeled (1) begins:
[1]; generation 1: 1->[4]; generation 2: 4->[7,10,13,16];
generation 3: 7->[10,13,16,19,22,25,28],
10->[13,16,19,22,25,28,31,34,37,40],
13->[16,19,22,25,28,31,34,37,40,43,46,49,52],
16->[19,22,25,28,31,34,37,40,43,46,49,52,55,58,61,64]; ...
Then a(n) gives the number of nodes in generation n.
Also, a(n+1) = sum of labels of nodes in generation n.
		

Links

• M. Cook and M. Kleber, Tournament sequences and Meeussen sequences, Electronic J. Comb. 7 (2000), #R44.

Crossrefs

Cf. A008934, A113077, A113078, A113079, A113085, A113089, A113098, A113100, A113107, A113109, A113111, A113113.

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