A187459 Number of (n+1)X(n+1) 0..2 arrays with all the 2X2 subblocks nonsingular and the array of 2X2 subblock determinants symmetric.

50, 1236, 89618, 11684688, 6112320620, 4871877392202, 17264863350746654, 83050637417670542044

Offset

1,1

Comments

Column 2 of A187462

Links

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

Example

Some solutions for 4X4
..2..2..2..0....1..1..1..2....1..1..2..0....2..1..2..2....0..2..0..2
..1..2..0..2....0..2..0..1....2..1..0..2....1..2..1..0....2..0..2..2
..2..0..1..1....1..0..2..2....2..0..1..0....2..1..2..2....0..2..1..2
..2..2..2..0....2..1..2..0....2..2..2..2....2..0..2..0....2..2..2..0

Crossrefs

Sequence in context: A318760 A250520 A017766 * A035720 A161695 A162492

Adjacent sequences: A187456 A187457 A187458 * A187460 A187461 A187462

Keyword

nonn

Author

R. H. Hardin, Mar 10 2011

Status

approved