A113680 Riordan array ((1-x-2x^2)/(1-x),x).

1, 0, 1, -2, 0, 1, -2, -2, 0, 1, -2, -2, -2, 0, 1, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, 0, 1, -2, -2, -2, -2, -2, -2, -2, -2

Offset

0,4

Comments

Inverse of A113678. Sequence array of A113679. Row sums are 3-2n-2*0^n. Diagonal sums are 1-n.

Links

Table of n, a(n) for n=0..85.

Formula

Number triangle T(n, k)=if(k<=n, C(0, n-k)+2*C(1, n-k)-2, 0).

Example

Triangle begins
1;
0, 1;
-2, 0, 1;
-2, -2, 0, 1;
-2, -2, -2, 0, 1;
-2, -2, -2, -2, 0, 1;

Crossrefs

Sequence in context: A101663 A284749 A062169 * A316723 A128187 A266477

Adjacent sequences: A113677 A113678 A113679 * A113681 A113682 A113683

Keyword

easy,sign,tabl

Author

Paul Barry, Nov 04 2005

Status

approved