login
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.
1

%I #10 Apr 07 2020 15:27:25

%S 1,1,7,106,3616,222190,22393101,3444274966,767013376954,

%T 237357745294502,98772845166962126,53805754052806007528,

%U 37518059561068661124848,32857132982034738756201764,35557273023840891076852950650,46882317669656858737974124606500,74388988137861405036759725929161668

%N 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 Number of n X n symmetric matrices with nonnegative integer entries and all row and column sums 6. - _Andrew Howroyd_, Apr 07 2020

%e All solutions for 12X2

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

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

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

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

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

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

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

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

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

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

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

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

%Y Row 6 of A188403.

%K nonn

%O 0,3

%A _R. H. Hardin_, Mar 30 2011

%E a(0)=1 prepended and terms a(10) and beyond from _Andrew Howroyd_, Apr 06 2020