A046792 Triangle of numbers where k-th row contains (ij)!/(i!j!) with i+j = k+1, 1 <= i <= k.

1, 1, 1, 1, 6, 1, 1, 60, 60, 1, 1, 840, 10080, 840, 1, 1, 15120, 3326400, 3326400, 15120, 1, 1, 332640, 1816214400, 36324288000, 1816214400, 332640, 1, 1, 8648640, 1482030950400, 844757641728000, 844757641728000, 1482030950400, 8648640, 1

Offset

1,5

Links

Andrew Howroyd, Table of n, a(n) for n = 1..210

Formula

T(n,k) = (k*(n+1-k))!/(k!*(n+1-k)!). - Andrew Howroyd, Mar 07 2020

Example

Triangle begins
  1;
  1,  1;
  1,  6,  1;
  1, 60, 60,  1;
  ...

Prog

(PARI) T(n, k)={(k*(n+1-k))!/(k!*(n+1-k)!)} \\ Andrew Howroyd, Mar 07 2020

Crossrefs

Sequence in context: A287020 A172375 A075377 * A209330 A357297 A111825

Adjacent sequences: A046789 A046790 A046791 * A046793 A046794 A046795

Keyword

nonn,tabl,easy

Author

N. J. A. Sloane

Extensions

More terms from James A. Sellers

Status

approved