A124846 Triangle read by rows: T(n,k) = (2 - (-1)^k)*binomial(n,k) (0 <= k <= n).

1, 1, 3, 1, 6, 1, 1, 9, 3, 3, 1, 12, 6, 12, 1, 1, 15, 10, 30, 5, 3, 1, 18, 15, 60, 15, 18, 1, 1, 21, 21, 105, 35, 63, 7, 3, 1, 24, 28, 168, 70, 168, 28, 24, 1, 1, 27, 36, 252, 126, 378, 84, 108, 9, 3, 1, 30, 45, 360, 210, 756, 210, 360, 45, 30, 1, 1, 33, 55, 495, 330, 1386, 462, 990

Offset

0,3

Links

Table of n, a(n) for n=0..73.

Example

First few rows of the triangle:
  1;
  1,  3;
  1,  6,  1;
  1,  9,  3,  3;
  1, 12,  6, 12,  1;
  1, 15, 10, 30,  5,  3;
  ...
A046055(4) = 16 = sum of row 4 terms (1 + 9 + 3 + 3).

Maple

T:=(n, k)->(2-(-1)^k)*binomial(n, k): for n from 0 to 12 do seq(T(n, k), k=0..n) od; # yields sequence in triangular form

Crossrefs

Cf. A010684, A046055, A124845.

Sequence in context: A347231 A213670 A116609 * A177375 A099512 A127096

Adjacent sequences: A124843 A124844 A124845 * A124847 A124848 A124849

Keyword

nonn,tabl

Author

Gary W. Adamson, Nov 10 2006

Extensions

Edited by N. J. A. Sloane, Nov 24 2006

Status

approved