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A283796 Triangle T(n,k) read by rows: the number of symmetric q-circulant n X n {0,1}-matrices where each row and each column sum equals k. 1
1, 1, 1, 1, 2, 1, 1, 4, 4, 1, 1, 6, 6, 6, 1, 1, 6, 12, 12, 6, 1, 1, 8, 18, 22, 18, 8, 1, 1, 8, 24, 38, 38, 24, 8, 1, 1, 16, 38, 80, 86, 80, 38, 16, 1, 1, 10, 40, 88, 132, 132, 88, 40, 10, 1, 1, 12, 50, 128, 220, 262, 220, 128, 50, 12, 1, 1, 12, 60, 170, 340, 472, 472, 340, 170, 60, 12, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

Obtained by selecting matrices in A283795 which are symmetric, which means where the transpose of the binary matrix equals the matrix.

Is column k=1 the same as A235384?

LINKS

Table of n, a(n) for n=0..77.

EXAMPLE

The matrix stars in rows n=0 and columns 0<=k<n as

1 rsum= 1

1 1 rsum= 2

1 2 1 rsum= 4

1 4 4 1 rsum= 10

1 6 6 6 1 rsum= 20

1 6 12 12 6 1 rsum= 38

1 8 18 22 18 8 1 rsum= 76

1 8 24 38 38 24 8 1 rsum= 142

1 16 38 80 86 80 38 16 1 rsum= 356

1 10 40 88 132 132 88 40 10 1 rsum= 542

1 12 50 128 220 262 220 128 50 12 1 rsum= 1084

1 12 60 170 340 472 472 340 170 60 12 1 rsum= 2110

1 24 92 282 586 936 1050 936 586 282 92 24 1 rsum= 4892

1 14 84 292 730 1302 1736 1736 1302 730 292 84 14 1 rsum= 8318

CROSSREFS

Cf. A235384, A045655.

Sequence in context: A026659 A026386 A147532 * A156580 A157528 A132731

Adjacent sequences:  A283793 A283794 A283795 * A283797 A283798 A283799

KEYWORD

tabl,nonn

AUTHOR

R. J. Mathar, Mar 16 2017

STATUS

approved

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Last modified October 23 14:45 EDT 2019. Contains 328345 sequences. (Running on oeis4.)