A213792 Number of n X n 0..n symmetric arrays with every row summing to floor(n^2/2).

1, 1, 3, 29, 3249, 4843626, 138198204339, 87098380004205128, 1525223999399549983474977

Offset

0,3

Links

Table of n, a(n) for n=0..8.

Example

Some solutions for n=4
..4..4..0..0....3..2..1..2....4..2..0..2....1..3..1..3....2..1..3..2
..4..4..0..0....2..1..2..3....2..0..4..2....3..4..0..1....1..4..0..3
..0..0..4..4....1..2..3..2....0..4..1..3....1..0..3..4....3..0..2..3
..0..0..4..4....2..3..2..1....2..2..3..1....3..1..4..0....2..3..3..0

Crossrefs

Diagonal of A213800.

Sequence in context: A319637 A003190 A322451 * A133663 A270480 A229051

Adjacent sequences: A213789 A213790 A213791 * A213793 A213794 A213795

Keyword

nonn,more

Author

R. H. Hardin, Jun 20 2012

Extensions

a(0)=1 prepended and a(7)-a(8) from Andrew Howroyd, Apr 07 2020

Status

approved