A188402 Number of (8*n) X 8 binary arrays with rows in nonincreasing order, n ones in every column and no more than 2 ones in any row.

1, 764, 213798, 22262244, 1158207312, 36218801244, 767013376954, 11930327925108, 144413237202513, 1419823497519000, 11712930348839580, 83160597646878696, 518506187445244096, 2885792129983693112, 14530215365239964244, 66929085400566337832, 284683656715082259137

Offset

0,2

Comments

Number of 8 X 8 symmetric matrices with nonnegative integer entries and all row and column sums n. - Andrew Howroyd, Apr 07 2020

Links

Table of n, a(n) for n=0..16.

Example

Some solutions for 16X8
..1..0..0..0..1..0..0..0....1..0..1..0..0..0..0..0....1..0..0..0..0..0..0..0
..1..0..0..0..1..0..0..0....1..0..0..1..0..0..0..0....1..0..0..0..0..0..0..0
..0..1..1..0..0..0..0..0....0..1..0..0..0..1..0..0....0..1..1..0..0..0..0..0
..0..1..0..0..0..0..1..0....0..1..0..0..0..0..0..0....0..1..0..0..0..0..0..0
..0..0..1..0..0..1..0..0....0..0..1..0..1..0..0..0....0..0..1..0..0..0..0..0
..0..0..0..1..0..0..1..0....0..0..0..1..0..0..0..0....0..0..0..1..0..0..0..1
..0..0..0..1..0..0..0..0....0..0..0..0..1..0..1..0....0..0..0..1..0..0..0..0
..0..0..0..0..0..1..0..0....0..0..0..0..0..1..0..1....0..0..0..0..1..0..1..0
..0..0..0..0..0..0..0..1....0..0..0..0..0..0..1..0....0..0..0..0..1..0..0..1
..0..0..0..0..0..0..0..1....0..0..0..0..0..0..0..1....0..0..0..0..0..1..1..0
..0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0....0..0..0..0..0..1..0..0
..0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0
..0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0
..0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0
..0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0
..0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0

Crossrefs

Column 8 of A188403.

Sequence in context: A238920 A054468 A156395 * A139674 A124412 A280972

Adjacent sequences: A188399 A188400 A188401 * A188403 A188404 A188405

Keyword

nonn

Author

R. H. Hardin, Mar 30 2011

Extensions

a(0)=1 prepended and terms a(9) and beyond from Andrew Howroyd, Apr 07 2020

Status

approved