A188401 Number of (7*n) X 7 binary arrays with rows in nonincreasing order, n ones in every column and no more than 2 ones in any row.

1, 232, 22054, 902962, 20758650, 313568636, 3444274966, 29445929253, 205617134345, 1214911142900, 6238854236951, 28428076580526, 116844463511314, 438968651731176, 1523790358321400, 4931487866349689, 14991891923697588, 43084786003434739, 117690415289036999

Offset

0,2

Comments

Number of 7 X 7 symmetric matrices with nonnegative integer entries and all row and column sums n. - Andrew Howroyd, Apr 07 2020

Links

Andrew Howroyd, Table of n, a(n) for n = 0..30

Example

Some solutions for 14X7
..1..1..0..0..0..0..0....1..1..0..0..0..0..0....1..1..0..0..0..0..0
..1..0..0..0..0..0..0....1..0..0..0..0..0..1....1..0..0..1..0..0..0
..0..1..0..0..1..0..0....0..1..0..1..0..0..0....0..1..0..0..1..0..0
..0..0..1..1..0..0..0....0..0..1..0..0..0..0....0..0..1..0..0..0..0
..0..0..1..0..0..0..0....0..0..1..0..0..0..0....0..0..1..0..0..0..0
..0..0..0..1..0..0..0....0..0..0..1..0..1..0....0..0..0..1..0..1..0
..0..0..0..0..1..0..1....0..0..0..0..1..0..0....0..0..0..0..1..0..0
..0..0..0..0..0..1..0....0..0..0..0..1..0..0....0..0..0..0..0..1..0
..0..0..0..0..0..1..0....0..0..0..0..0..1..1....0..0..0..0..0..0..1
..0..0..0..0..0..0..1....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

Crossrefs

Column 7 of A188403.

Sequence in context: A234682 A156391 A279660 * A307827 A206793 A206970

Adjacent sequences: A188398 A188399 A188400 * A188402 A188403 A188404

Keyword

nonn

Author

R. H. Hardin, Mar 30 2011

Extensions

a(0)=1 prepended and terms a(11) and beyond from Andrew Howroyd, Apr 07 2020

Status

approved