A284990 Triangle T(n,t) read by rows: the number of n X n {0,1} matrices with trace t where each row sum and each column sum is 3.

1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 6, 8, 9, 44, 210, 420, 610, 540, 216, 7570, 33120, 66870, 82080, 66870, 33120, 7570, 1975560, 8171730, 15729000, 18433415, 14372820, 7499940, 2398900, 357435, 749649145, 2971510080, 5508175260, 6267658544, 4815171270, 2570369760, 932429820, 209185200, 22040361

Offset: 0

Author

R. J. Mathar, Apr 07 2017

Keywords

• nonn
• tabl

Examples

			0:        1
1:        0       0
2:        0       0        0
3:        0       0        0        1
4:        1       0        6        8        9
5:       44     210      420      610      540     216
6:     7570   33120    66870    82080    66870   33120    7570
7:  1975560 8171730 15729000 18433415 14372820 7499940 2398900 357435
		

Links

• Alois P. Heinz, Rows n = 0..11, flattened
• Index entries for sequences related to binary matrices

Crossrefs

Cf. A007107 (diagonal?), A001501 (row sums), A007105 (column 0?), A110040 (symmetric matrices).

Extensions

More terms from Alois P. Heinz, Apr 09 2017