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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.
5
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
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
KEYWORD
nonn,tabl
AUTHOR
R. J. Mathar, Apr 07 2017
EXTENSIONS
More terms from Alois P. Heinz, Apr 09 2017
STATUS
approved