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

0,18

Links

Alois P. Heinz, Rows n = 0..10, flattened

Index entries for sequences related to binary matrices

Example

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

Crossrefs

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

Sequence in context: A110804 A048063 A007927 * A327692 A269234 A160517

Adjacent sequences: A284988 A284989 A284990 * A284992 A284993 A284994

Keyword

nonn,tabl

Author

R. J. Mathar, Apr 07 2017

Extensions

More terms from Alois P. Heinz, Apr 09 2017

Status

approved