A171661 Triangle T(n,k) (n >= 0, 0 <= k <= n) read by rows: T(n,0) = T(n,1) = A000984(n); for n >= 2 and k >= 2, T(n,k) = T(n,k-1) - T(n-1,k-2).

1, 2, 2, 6, 6, 4, 20, 20, 14, 8, 70, 70, 50, 30, 16, 252, 252, 182, 112, 62, 32, 924, 924, 672, 420, 238, 126, 64, 3432, 3432, 2508, 1584, 912, 492, 254, 128, 12870, 12870, 9438, 6006, 3498, 1914, 1002, 510, 256, 48620, 48620, 35750, 22880, 13442, 7436

Offset

0,2

Links

Table of n, a(n) for n=0..50.

Example

Triangle starts:
1
2,2
6,6,4
20,20,14,8
70,70,50,30,16

Crossrefs

Cf. A000984, A172021.

Sequence in context: A033712 A033730 A033754 * A276418 A173869 A247377

Adjacent sequences: A171658 A171659 A171660 * A171662 A171663 A171664

Keyword

nonn,tabl

Author

Mark Dols, Dec 14 2009

Extensions

Edited by N. J. A. Sloane, Jan 24 2010

More terms from Mark Dols, Jan 24 2010

Status

approved