A124819 Number triangle T(n,k)=C(n+2k+1,3k+1).

1, 2, 1, 3, 5, 1, 4, 15, 8, 1, 5, 35, 36, 11, 1, 6, 70, 120, 66, 14, 1, 7, 126, 330, 286, 105, 17, 1, 8, 210, 792, 1001, 560, 153, 20, 1, 9, 330, 1716, 3003, 2380, 969, 210, 23, 1, 10, 495, 3432, 8008, 8568, 4845, 1540, 276

Offset: 0

Author

Paul Barry, Nov 08 2006

Keywords

• easy
• nonn
• tabl

Comments

Row sums are A124820. Diagonal sums are A052921. Inverse is A124821.

Examples

			Triangle begins
1,
2, 1,
3, 5, 1,
4, 15, 8, 1,
5, 35, 36, 11, 1,
6, 70, 120, 66, 14, 1,
7, 126, 330, 286, 105, 17, 1,
8, 210, 792, 1001, 560, 153, 20, 1
		

Formula

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