A231377 Number of n X 3 0..1 arrays with no element less than a strict majority of its horizontal and vertical neighbors.

4, 21, 93, 378, 1519, 6126, 24747, 99964, 403743, 1630662, 6586087, 26600572, 107437031, 433927396, 1752589551, 7078534592, 28589495207, 115470119764, 466372299261, 1883631211124, 7607798625811, 30727139997676, 124103854340837

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 16*a(n-3) - 14*a(n-4) - 3*a(n-5) + 8*a(n-6) - 9*a(n-7) - 2*a(n-8) + 6*a(n-9) + 2*a(n-10) for n>11.

Empirical g.f.: x*(4 - 3*x + 11*x^2 - 13*x^3 - 6*x^4 - 12*x^5 - 15*x^6 + 3*x^7 + 13*x^8 + 8*x^9 + 2*x^10) / (1 - 6*x + 11*x^2 - 16*x^3 + 14*x^4 + 3*x^5 - 8*x^6 + 9*x^7 + 2*x^8 - 6*x^9 - 2*x^10). - Colin Barker, Sep 28 2018

Example

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

Crossrefs

Column 3 of A231382.

Sequence in context: A328345 A371309 A220574 * A017967 A292308 A076901

Adjacent sequences: A231374 A231375 A231376 * A231378 A231379 A231380

Keyword

nonn

Author

R. H. Hardin, Nov 08 2013

Status

approved