A218280 Hilltop maps: number of n X n binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or vertical neighbor in a random 0..4 n X n array

1, 15, 511, 65507, 33549827, 68710447465, 562876144341077

Offset

1,2

Comments

Diagonal of A218288

Links

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

Example

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

Crossrefs

Sequence in context: A203326 A092561 A218312 * A218632 A218235 A212739

Adjacent sequences: A218277 A218278 A218279 * A218281 A218282 A218283

Keyword

nonn

Author

R. H. Hardin Oct 25 2012

Status

approved