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Number of (7*n) X n binary arrays with rows in nonincreasing order, 7 ones in every column and no more than 2 ones in any row.
1

%I #11 Apr 07 2020 15:29:27

%S 1,1,8,154,7340,681460,111200600,29445929253,11930327925108,

%T 7061916086148812,5884543061841730064,6695191219474600587460,

%U 10138670050730337096234992,19996250425584243540741431296,50416254105984511132422687541856,159887463958073530310081258765881180

%N Number of (7*n) X n binary arrays with rows in nonincreasing order, 7 ones in every column and no more than 2 ones in any row.

%C Number of n X n symmetric matrices with nonnegative integer entries and all row and column sums 7. - _Andrew Howroyd_, Apr 07 2020

%e All solutions for 14X2

%e ..1..1....1..1....1..1....1..1....1..1....1..1....1..0....1..1

%e ..1..1....1..1....1..1....1..1....1..1....1..0....1..0....1..1

%e ..1..0....1..1....1..1....1..1....1..1....1..0....1..0....1..1

%e ..1..0....1..1....1..1....1..1....1..1....1..0....1..0....1..0

%e ..1..0....1..0....1..1....1..1....1..1....1..0....1..0....1..0

%e ..1..0....1..0....1..1....1..0....1..1....1..0....1..0....1..0

%e ..1..0....1..0....1..0....1..0....1..1....1..0....1..0....1..0

%e ..0..1....0..1....0..1....0..1....0..0....0..1....0..1....0..1

%e ..0..1....0..1....0..0....0..1....0..0....0..1....0..1....0..1

%e ..0..1....0..1....0..0....0..0....0..0....0..1....0..1....0..1

%e ..0..1....0..0....0..0....0..0....0..0....0..1....0..1....0..1

%e ..0..1....0..0....0..0....0..0....0..0....0..1....0..1....0..0

%e ..0..0....0..0....0..0....0..0....0..0....0..1....0..1....0..0

%e ..0..0....0..0....0..0....0..0....0..0....0..0....0..1....0..0

%Y Row 7 of A188403.

%K nonn

%O 0,3

%A _R. H. Hardin_, Mar 30 2011

%E a(0)=1 prepended and terms a(9) and beyond from _Andrew Howroyd_, Apr 06 2020