A269744 Triangle read by rows: number of generic n-rook placements with k rooks below the main diagonal.

1, 4, 7, 26, 68, 75, 236, 940, 1090, 1105, 2752, 16645, 20360, 20790, 20821, 39208, 360081, 464111, 477242, 478376, 478439, 660032, 9202170, 12492277, 12933423, 12974826, 12977688, 12977815

Offset: 1

Author

N. J. A. Sloane, Mar 16 2016

Keywords

• nonn
• tabl
• more

Examples

			Triangle begins:
1,
4,7,
26,68,75,
236,940,1090,1105,
2752,16645,20360,20790,20821,
39208,360081,464111,477242,478376,478439,
660032,9202170,12492277,12933423,12974826,12977688,12977815,
...
		

Links

• E. Banaian, S. Butler, C. Cox, J. Davis, J. Landgraf and S. Ponce, A generalization of Eulerian numbers via rook placements, arXiv:1508.03673 [math.CO], 2015.
• A. N. Bhavale, B. N. Waphare, Basic retracts and counting of lattices, Australasian J. of Combinatorics (2020) Vol. 78, No. 1, 73-99.