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, 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

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