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A218228 Hilltop maps: number of nX3 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, vertical or antidiagonal neighbor in a random 0..2 nX3 array 1
7, 61, 497, 3969, 31739, 253825, 2029849, 16232833, 129815047, 1038139593, 8302071585, 66392220265, 530943014251, 4245986702321, 33955438893389, 271543909879097, 2171554761048415, 17366068280933465, 138877606472351657 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A218233

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 7*a(n-1) +7*a(n-2) +7*a(n-3) +5*a(n-4) +9*a(n-5) +9*a(n-6) +9*a(n-7) +8*a(n-8) +4*a(n-9) +a(n-10) +a(n-11) +a(n-12) +a(n-13) -a(n-14) -a(n-15) -a(n-16) -a(n-17)

EXAMPLE

Some solutions for n=3

..1..1..1....1..1..0....1..1..1....0..1..1....1..1..0....0..0..1....1..1..0

..1..1..0....0..1..1....0..0..0....0..1..0....0..0..0....1..1..0....1..1..1

..0..1..1....0..1..0....0..1..0....0..1..1....0..0..1....1..0..1....0..1..1

CROSSREFS

Sequence in context: A135165 A218805 A164943 * A155599 A104093 A015572

Adjacent sequences:  A218225 A218226 A218227 * A218229 A218230 A218231

KEYWORD

nonn

AUTHOR

R. H. Hardin Oct 24 2012

STATUS

approved

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Last modified April 16 21:58 EDT 2021. Contains 343051 sequences. (Running on oeis4.)