A116948 Riordan array ((1+2x^2)/(1-x^3),x).

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

Offset: 0

Author

Paul Barry, Mar 29 2006

Keywords

• easy
• nonn
• tabl

Comments

Row sums are A117571. Diagonal sums are A117572. Inverse is A116949.

Examples

			Triangle begins
1,
0, 1,
2, 0, 1,
1, 2, 0, 1,
0, 1, 2, 0, 1,
2, 0, 1, 2, 0, 1,
1, 2, 0, 1, 2, 0, 1,
0, 1, 2, 0, 1, 2, 0, 1,
2, 0, 1, 2, 0, 1, 2, 0, 1
		

Formula

Number triangle T(n,k)=2*J(L((n-k+2)/3))[k<=n] where L(j/p) is the Legendre symbol of j and p and J(n)=A001045(n)