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

0,2

Comments

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

Links

Table of n, a(n) for n=0..52.

Formula

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

Example

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

Crossrefs

Sequence in context: A208752 A119308 A110197 * A124019 A337886 A337884

Adjacent sequences: A124816 A124817 A124818 * A124820 A124821 A124822

Keyword

easy,nonn,tabl

Author

Paul Barry, Nov 08 2006

Status

approved