A186160 1/4 the number of n X n 0..3 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors

0, 7, 702, 751266, 5033988714, 268995986029278

Offset

1,2

Comments

Diagonal of A186168

Links

Table of n, a(n) for n=1..6.

Example

Some solutions for 4X4 with a(1,1)=0
..0..2..0..2....0..0..2..0....0..2..1..1....0..0..2..2....0..2..2..1
..0..2..0..2....0..0..2..0....0..2..0..0....0..2..1..2....0..0..0..1
..1..2..3..3....2..3..3..3....2..1..1..0....2..2..1..0....2..3..3..1
..1..1..1..1....2..3..2..2....2..2..1..0....3..3..3..0....2..3..0..0

Crossrefs

Sequence in context: A163016 A261696 A174855 * A129291 A229149 A159815

Adjacent sequences: A186157 A186158 A186159 * A186161 A186162 A186163

Keyword

nonn

Author

R. H. Hardin Feb 13 2011

Status

approved