A198597 Number of 2nX2n 0..3 arrays with values 0..3 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors

1, 5, 674, 844228, 8055413256

Offset

1,2

Comments

Diagonal of A198604

Links

Table of n, a(n) for n=1..5.

Example

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

Crossrefs

Sequence in context: A332165 A133750 A203925 * A180315 A332300 A242193

Adjacent sequences: A198594 A198595 A198596 * A198598 A198599 A198600

Keyword

nonn

Author

R. H. Hardin Oct 27 2011

Status

approved