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A188407 Number of (6*n) X n binary arrays with rows in nonincreasing order, 6 ones in every column and no more than 2 ones in any row.

%I A188407 #10 Apr 07 2020 15:27:25
%S A188407 1,1,7,106,3616,222190,22393101,3444274966,767013376954,
%T A188407 237357745294502,98772845166962126,53805754052806007528,
%U A188407 37518059561068661124848,32857132982034738756201764,35557273023840891076852950650,46882317669656858737974124606500,74388988137861405036759725929161668
%N A188407 Number of (6*n) X n binary arrays with rows in nonincreasing order, 6 ones in every column and no more than 2 ones in any row.
%C A188407 Number of n X n symmetric matrices with nonnegative integer entries and all row and column sums 6. - _Andrew Howroyd_, Apr 07 2020
%e A188407 All solutions for 12X2
%e A188407 ..1..0....1..1....1..1....1..1....1..1....1..1....1..1
%e A188407 ..1..0....1..1....1..0....1..1....1..1....1..1....1..1
%e A188407 ..1..0....1..1....1..0....1..0....1..1....1..1....1..1
%e A188407 ..1..0....1..1....1..0....1..0....1..1....1..1....1..0
%e A188407 ..1..0....1..0....1..0....1..0....1..1....1..1....1..0
%e A188407 ..1..0....1..0....1..0....1..0....1..0....1..1....1..0
%e A188407 ..0..1....0..1....0..1....0..1....0..1....0..0....0..1
%e A188407 ..0..1....0..1....0..1....0..1....0..0....0..0....0..1
%e A188407 ..0..1....0..0....0..1....0..1....0..0....0..0....0..1
%e A188407 ..0..1....0..0....0..1....0..1....0..0....0..0....0..0
%e A188407 ..0..1....0..0....0..1....0..0....0..0....0..0....0..0
%e A188407 ..0..1....0..0....0..0....0..0....0..0....0..0....0..0
%Y A188407 Row 6 of A188403.
%K A188407 nonn
%O A188407 0,3
%A A188407 _R. H. Hardin_, Mar 30 2011
%E A188407 a(0)=1 prepended and terms a(10) and beyond from _Andrew Howroyd_, Apr 06 2020