OFFSET
0,2
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
EXAMPLE
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
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 20 2002
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
STATUS
approved