A187668 Number of (n+1)X(n+1) 0..1 arrays with each 2X2 subblock nonsingular and the array of 2X2 subblock determinants symmetric about the diagonal and antidiagonal

6, 24, 112, 974, 9928, 197152, 4547688, 200947508, 10553936856, 1051895421812, 125339066655024, 28078885802576900, 7575400864257725704

Offset

1,1

Comments

Column 1 of A187670

Links

Table of n, a(n) for n=1..13.

Example

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

Crossrefs

Sequence in context: A122739 A038380 A052745 * A273813 A293257 A223752

Adjacent sequences: A187665 A187666 A187667 * A187669 A187670 A187671

Keyword

nonn

Author

R. H. Hardin Mar 12 2011

Status

approved