A218365 Hilltop maps: number of n X n binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, vertical or antidiagonal neighbor in a random 0..3 n X n array.

1, 15, 509, 65409, 33488029, 68583014753, 561830980890331, 18410060198369526671

Offset

1,2

Comments

Diagonal of A218372

Links

Table of n, a(n) for n=1..8.

Example

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

Crossrefs

Sequence in context: A249962 A004703 A218188 * A203326 A092561 A218312

Adjacent sequences: A218362 A218363 A218364 * A218366 A218367 A218368

Keyword

nonn

Author

R. H. Hardin, Oct 27 2012

Status

approved