A200794 Number of n X n 0..3 arrays with values 0..3 introduced in row major order and each element equal to no more than two horizontal and vertical neighbors

1, 15, 9880, 132636590, 26207146328784, 75743730886453371522, 3202145671418507455058837791

Offset

1,2

Comments

Diagonal of A200801

Links

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

Example

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

Crossrefs

Sequence in context: A308156 A304397 A206593 * A230173 A271403 A198720

Adjacent sequences: A200791 A200792 A200793 * A200795 A200796 A200797

Keyword

nonn

Author

R. H. Hardin Nov 22 2011

Status

approved