A187458 Number of (n+1)X(n+1) 0..1 arrays with all the 2X2 subblocks nonsingular and the array of 2X2 subblock determinants symmetric

6, 26, 144, 1272, 15192, 286392, 7648032, 314011868, 18986004296, 1725663296600, 237096836118080, 48071903199959400, 15027587384189632928, 6819730931931151055960, 4852231403635188536789728

Offset

1,1

Comments

Column 1 of A187462

Links

R. H. Hardin, Table of n, a(n) for n = 1..18

Example

Some solutions for 4X4
..1..1..0..1....1..0..1..1....0..1..0..1....1..0..1..1....1..0..1..0
..1..0..1..0....0..1..0..1....1..0..1..0....0..1..0..1....1..1..1..1
..0..1..0..1....1..0..1..1....1..1..0..1....1..0..1..1....1..0..1..0
..1..0..1..1....0..1..0..1....1..0..1..1....1..1..1..0....0..1..1..1

Crossrefs

Sequence in context: A339685 A364744 A144037 * A100308 A352694 A049040

Adjacent sequences: A187455 A187456 A187457 * A187459 A187460 A187461

Keyword

nonn

Author

R. H. Hardin Mar 10 2011

Status

approved