A284991 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 4.

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 10, 20, 45, 44, 265, 1920, 6300, 13720, 20175, 18000, 7570, 357435, 2398900, 7499940, 14372820, 18433415, 15729000, 8171730, 1975560, 749649145, 4695264000, 13718863480, 24545693760, 29544855480, 24545693760, 13718863480, 4695264000, 749649145

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        0
4:       0       0       0        0        1
5:       1       0      10       20       45       44
6:     265    1920    6300    13720    20175    18000    7570
7:  357435 2398900 7499940 14372820 18433415 15729000 8171730 1975560
		

Links

• Alois P. Heinz, Rows n = 0..10, flattened
• Index entries for sequences related to binary matrices

Crossrefs

Cf. A058528 (row sums), A007105 (diagonal?), A139670 (symmetric matrices).

Extensions

More terms from Alois P. Heinz, Apr 09 2017