A067209 Number of n X n 0..1 matrices with all row and column sums equal.

1, 2, 4, 14, 140, 4322, 434542, 144109562, 165431317452, 654143160457922, 9331115832294448754, 469229841129645179004962, 87481268294773501231007850158, 58328998963405322376273800187396962, 147013017541698957281403494604070439260442

Offset: 0

Author

R. H. Hardin, Feb 20 2002

Keywords

• nonn

Examples

			Some solutions for n=5
..1..1..0..0..1....0..0..1..0..1....0..1..0..1..1....1..1..0..1..0
..1..1..0..0..1....1..1..0..0..0....1..1..0..0..1....1..0..1..1..0
..0..0..1..1..1....1..0..0..1..0....1..1..1..0..0....1..0..1..0..1
..1..0..1..1..0....0..1..1..0..0....0..0..1..1..1....0..1..0..1..1
..0..1..1..1..0....0..0..0..1..1....1..0..1..1..0....0..1..1..0..1
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..30
• E. R. Canfield and B. D. McKay, Asymptotic enumeration of dense 0-1 matrices with equal row and column sums
• B. D. McKay, 0-1 matrices with constant row and column sums

Crossrefs

Row sums of A008300.

Column k=1 of A202784.

Extensions

Added one term and example - R. H. Hardin, Jan 05 2012

a(0)=1 prepended and more terms (using data provided by B. D. McKay) from Alois P. Heinz, Apr 12 2017