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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

%I #7 Mar 16 2017 17:36:48

%S 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,

%T 38,38,24,8,1,1,16,38,80,86,80,38,16,1,1,10,40,88,132,132,88,40,10,1,

%U 1,12,50,128,220,262,220,128,50,12,1,1,12,60,170,340,472,472,340,170,60,12,1

%N 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.

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

%C Is column k=1 the same as A235384?

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

%e 1 rsum= 1

%e 1 1 rsum= 2

%e 1 2 1 rsum= 4

%e 1 4 4 1 rsum= 10

%e 1 6 6 6 1 rsum= 20

%e 1 6 12 12 6 1 rsum= 38

%e 1 8 18 22 18 8 1 rsum= 76

%e 1 8 24 38 38 24 8 1 rsum= 142

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

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

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

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

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

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

%Y Cf. A235384, A045655.

%K tabl,nonn

%O 0,5

%A _R. J. Mathar_, Mar 16 2017

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Last modified April 26 17:59 EDT 2024. Contains 372003 sequences. (Running on oeis4.)