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

0,13

Links

Alois P. Heinz, Rows n = 0..11, flattened

Index entries for sequences related to binary matrices

Example

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

Crossrefs

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

Sequence in context: A342649 A254321 A174213 * A238621 A099102 A001743

Adjacent sequences: A284987 A284988 A284989 * A284991 A284992 A284993

Keyword

nonn,tabl

Author

R. J. Mathar, Apr 07 2017

Extensions

More terms from Alois P. Heinz, Apr 09 2017

Status

approved