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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 0
1, 15, 511, 65507, 33549827, 68710447465, 562876144341077 (list; graph; refs; listen; history; text; internal format)
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

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Last modified January 18 15:16 EST 2021. Contains 340254 sequences. (Running on oeis4.)