A155795 Triangle read by rows: t(n,k)=n!/(n - k*(n - k)).

1, 1, 1, 1, 2, 1, 1, 6, 6, 1, 1, 24, 24, 24, 1, 1, 120, 0, 0, 120, 1, 1, 720, 0, 0, 0, 720, 1, 1, 5040, 0, 0, 0, 0, 5040, 1, 1, 40320, 0, 0, 0, 0, 0, 40320, 1, 1, 362880, 0, 0, 0, 0, 0, 0, 362880, 1, 1, 3628800, 0, 0, 0, 0, 0, 0, 0, 3628800, 1

Offset

0,5

Comments

Row sums are: {1, 2, 4, 14, 74, 242, 1442, 10082, 80642, 725762, 7257602,...}.

Second column is n!.

Links

Table of n, a(n) for n=0..65.

Example

{1},
{1, 1},
{1, 2, 1},
{1, 6, 6, 1},
{1, 24, 24, 24, 1},
{1, 120, 0, 0, 120, 1},
{1, 720, 0, 0, 0, 720, 1},
{1, 5040, 0, 0, 0, 0, 5040, 1},
{1, 40320, 0, 0, 0, 0, 0, 40320, 1},
{1, 362880, 0, 0, 0, 0, 0, 0, 362880, 1},
{1, 3628800, 0, 0, 0, 0, 0, 0, 0, 3628800, 1}

Mathematica

Table[Table[n!/(n - k*(n - k))!, {k, 0, n}], {n, 0, 10}];
Flatten[%]

Crossrefs

Sequence in context: A172373 A174411 A322620 * A009963 A008300 A321789

Adjacent sequences: A155792 A155793 A155794 * A155796 A155797 A155798

Keyword

nonn,tabl

Author

Roger L. Bagula, Jan 27 2009

Extensions

Edited by N. J. A. Sloane, Jan 31 2009

Status

approved