A227636 Number of n X n 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X(n+1) binary array having determinant equal to one, with rows and columns of the latter in nondecreasing lexicographic order

1, 5, 39, 667, 25241, 2139328, 420651813, 196026480660

Offset

1,2

Comments

Diagonal of A227641

Links

Table of n, a(n) for n=1..8.

Example

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

Crossrefs

Sequence in context: A352658 A221412 A193118 * A118991 A253920 A156378

Adjacent sequences: A227633 A227634 A227635 * A227637 A227638 A227639

Keyword

nonn

Author

R. H. Hardin Jul 18 2013

Status

approved