A206669 Number of (n+1) X (n+1) 0..2 arrays with no 2 X 2 subblock having the same number of clockwise edge increases as its horizontal neighbors or the same number of counterclockwise edge increases as its vertical neighbors.

81, 1812, 57258, 2046168, 117968049, 9838056114, 1530071121621

Offset

1,1

Comments

Diagonal of A206676.

Links

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

Example

Some solutions for n=4:
..0..0..0..1..1....2..2..0..1..2....2..0..2..1..0....1..2..1..2..2
..0..0..1..0..0....0..2..1..1..0....2..1..1..0..0....1..0..1..0..2
..2..2..0..0..0....1..0..1..1..2....0..1..1..0..0....1..2..2..2..0
..0..1..1..2..1....0..0..2..0..0....0..2..2..1..0....1..2..2..1..0
..0..1..1..0..0....0..0..1..1..2....1..2..2..2..1....0..1..1..2..0

Crossrefs

Sequence in context: A236057 A205910 A236811 * A223206 A296650 A233371

Adjacent sequences: A206666 A206667 A206668 * A206670 A206671 A206672

Keyword

nonn

Author

R. H. Hardin, Feb 11 2012

Status

approved