A197236 Number of n X n 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 4,3,2,1,2 for x=0,1,2,3,4.

1, 2, 15, 231, 10649, 1209990, 352842084, 271939715540, 541622294917014

Offset

1,2

Comments

Every 0 is next to 0 4's, every 1 is next to 1 3's, every 2 is next to 2 2's, every 3 is next to 3 1's, every 4 is next to 4 2's.

Links

Table of n, a(n) for n=1..9.

Example

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

Crossrefs

Diagonal of A197242.

Sequence in context: A090301 A297087 A247660 * A097628 A305111 A216860

Adjacent sequences: A197233 A197234 A197235 * A197237 A197238 A197239

Keyword

nonn,more

Author

R. H. Hardin, Oct 12 2011

Status

approved