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A231509 Number of n X 2 0..1 arrays with no element less than a strict majority of its horizontal, vertical, diagonal and antidiagonal neighbors. 1
2, 6, 14, 35, 90, 225, 569, 1441, 3640, 9208, 23293, 58912, 149023, 376961, 953533, 2412030, 6101388, 15433867, 39041066, 98757133, 249813189, 631920345, 1598487728, 4043489236, 10228295949, 25873208028, 65448135355, 165555752805 (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) + a(n-2) + 3*a(n-3) - 4*a(n-4) - 2*a(n-5) - 4*a(n-6).

Empirical g.f.: x*(2 + 2*x - 5*x^3 - 4*x^4 - 4*x^5) / (1 - 2*x - x^2 - 3*x^3 + 4*x^4 + 2*x^5 + 4*x^6). - Colin Barker, Sep 29 2018

EXAMPLE

Some solutions for n=7:

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

..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0

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

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

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

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

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

CROSSREFS

Column 2 of A231515.

Sequence in context: A105635 A178320 A297187 * A318018 A025257 A283438

Adjacent sequences:  A231506 A231507 A231508 * A231510 A231511 A231512

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 09 2013

STATUS

approved

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Last modified March 4 08:38 EST 2021. Contains 341781 sequences. (Running on oeis4.)