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A284989 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 2. 3
1, 0, 0, 0, 0, 1, 1, 0, 3, 2, 9, 24, 24, 24, 9, 216, 540, 610, 420, 210, 44, 7570, 18000, 20175, 13720, 6300, 1920, 265, 357435, 829920, 909741, 617610, 284235, 91140, 19005, 1854, 22040361, 50223600, 54295528, 36663312, 17072790, 5679184, 1337280, 203952, 14833 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,9

LINKS

Alois P. Heinz, Rows n = 0..14, flattened

Index entries for sequences related to binary matrices

EXAMPLE

0:         1

1:         0        0

2:         0        0        1

3:         1        0        3        2

4:         9       24       24       24        9

5:       216      540      610      420      210      44

6:      7570    18000    20175    13720     6300    1920     265

7:    357435   829920   909741   617610   284235   91140   19005   1854

8:  22040361 50223600 54295528 36663312 17072790 5679184 1337280 203952 14833

CROSSREFS

Cf. A001499 (row sums), A000166 (diagonal), A007107 (column 0).

Cf. A008290, A098825, A284990, A284991.

Sequence in context: A118791 A234840 A234743 * A049971 A234748 A156528

Adjacent sequences:  A284986 A284987 A284988 * A284990 A284991 A284992

KEYWORD

nonn,tabl

AUTHOR

R. J. Mathar, Apr 07 2017

STATUS

approved

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Last modified June 28 17:16 EDT 2017. Contains 288839 sequences.