A124845 Triangle read by rows: T(n,k) = (3 - (-1)^k)*binomial(n,k)/2 (0 <= k <= n).

1, 1, 2, 1, 4, 1, 1, 6, 3, 2, 1, 8, 6, 8, 1, 1, 10, 10, 20, 5, 2, 1, 12, 15, 40, 15, 12, 1, 1, 14, 21, 70, 35, 42, 7, 2, 1, 16, 28, 112, 70, 112, 28, 16, 1, 1, 18, 36, 168, 126, 252, 84, 72, 9, 2, 1, 20, 45, 240, 210, 504, 210, 240, 45, 20, 1, 1, 22, 55, 330, 330, 924, 462, 660, 165

Offset

0,3

Links

Table of n, a(n) for n=0..74.

Example

First few rows of the triangle:
  1;
  1,  2;
  1,  4,  1;
  1,  6,  3,  2;
  1,  8,  6,  8,  1;
  1, 10, 10, 20,  5,  2;
  1, 12, 15, 40, 15, 12,  1;
  ...
Row 3 sum = 12 = (1 + 6 + 3 + 2) = A003945(3).

Maple

T:=(n, k)->(3-(-1)^k)*binomial(n, k)/2: for n from 0 to 12 do seq(T(n, k), k=0..n) od; # yields sequence in triangular form

Crossrefs

Cf. A003945.

Sequence in context: A247073 A124428 A191310 * A191392 A127625 A124844

Adjacent sequences: A124842 A124843 A124844 * A124846 A124847 A124848

Keyword

nonn,tabl

Author

Gary W. Adamson, Nov 10 2006

Extensions

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

Status

approved