A226865 Number of n X n (-1,0,1) arrays of determinants of 2X2 subblocks of some (n+1)X(n+1) binary array with rows and columns of the latter in lexicographically nondecreasing order

2, 13, 187, 6195, 523701, 119835087, 77611438870

Offset

1,1

Comments

Diagonal of A226870

Links

Table of n, a(n) for n=1..7.

Example

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

Crossrefs

Sequence in context: A073178 A193192 A356491 * A062156 A371318 A323209

Adjacent sequences: A226862 A226863 A226864 * A226866 A226867 A226868

Keyword

nonn

Author

R. H. Hardin Jun 20 2013

Status

approved