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

Author

R. H. Hardin, Nov 08 2013

Keywords

• nonn

Examples

			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
		

Links

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

Crossrefs

Column 3 of A231382.

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