A213692 Half the number of (n+1) X (n+1) symmetric 0..3 arrays with no 2 X 2 subblock summing to 6.

28, 1320, 208072, 109820000, 193946752094, 1146407046198040, 22678299640600736258, 1501445596428593204920908, 332684482425964910985336666019, 246706401290583205383638262307956104

Offset: 1

Author

R. H. Hardin Jun 18 2012

Keywords

• nonn

Comments

Column 3 of A213697.

Examples

			Some solutions for n=4
..0..2..1..0..1....0..0..1..2..0....0..0..3..0..1....2..1..1..2..1
..2..0..2..2..1....0..3..3..1..1....0..1..3..1..2....1..1..0..2..0
..1..2..0..3..1....1..3..0..1..2....3..3..2..1..0....1..0..3..0..0
..0..2..3..1..2....2..1..1..1..1....0..1..1..3..3....2..2..0..2..1
..1..1..1..2..0....0..1..2..1..0....1..2..0..3..2....1..0..0..1..1
		

Crossrefs

Cf. A213697.