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A238649 Number of (n+2) X (3+2) 0..1 arrays with no element equal to all horizontal neighbors or equal to all vertical neighbors, and new values 0..1 introduced in row major order. 1
3, 18, 51, 189, 630, 2187, 7473, 25692, 88119, 302511, 1038144, 3563151, 12228903, 41971050, 144048471, 494389041, 1696791534, 5823557223, 19987023645, 68597444364, 235433215419, 808030095435, 2773239244320, 9518031521451 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) + 5*a(n-2) - a(n-4).

Empirical g.f.: 3*x*(1 + 4*x - x^3) / (1 - 2*x - 5*x^2 + x^4). - Colin Barker, Oct 24 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

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

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

CROSSREFS

Column 3 of A238654.

Sequence in context: A304976 A064043 A267639 * A268484 A085789 A027334

Adjacent sequences:  A238646 A238647 A238648 * A238650 A238651 A238652

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 02 2014

STATUS

approved

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Last modified December 3 22:32 EST 2021. Contains 349468 sequences. (Running on oeis4.)