A109221 A number triangle related to the Fibonacci polynomials.

1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 5, 3, 1, 1, 1, 7, 5, 6, 1, 1, 1, 9, 7, 15, 6, 1, 1, 1, 11, 9, 28, 15, 10, 1, 1, 1, 13, 11, 45, 28, 35, 10, 1, 1, 1, 15, 13, 66, 45, 84, 35, 15, 1, 1, 1, 17, 15, 91, 66, 165, 84, 70, 15, 1, 1, 1, 19, 17, 120, 91, 286, 165, 210, 70, 21, 1, 1, 1, 21, 19

Offset

0,9

Comments

The repeated columns are made up by taking every second element of columns in A011973. Row sums are A109222.

Links

Table of n, a(n) for n=0..81.

Formula

Number triangle T(n, k)=binomial(floor((2n-k)/2)+n-k, 2n-2k)

Example

Rows begin
1;
1,1;
1,1,1;
1,1,3,1;
1,1,5,3,1;
1,1,7,5,6,1;

Crossrefs

Sequence in context: A081060 A255811 A131268 * A369227 A360908 A351347

Adjacent sequences: A109218 A109219 A109220 * A109222 A109223 A109224

Keyword

easy,nonn,tabl

Author

Paul Barry, Jun 22 2005

Status

approved