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A046792 Triangle of numbers where k-th row contains (ij)!/(i!j!) with i+j = k+1, 1 <= i <= k. 1
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 (list; table; graph; refs; listen; history; text; internal format)
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 A111825 A085552

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

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Last modified July 6 23:56 EDT 2020. Contains 335484 sequences. (Running on oeis4.)