A231376 Number of n X 2 0..1 arrays with no element less than a strict majority of its horizontal and vertical neighbors.

2, 10, 21, 48, 113, 261, 601, 1390, 3216, 7435, 17190, 39751, 91921, 212555, 491510, 1136570, 2628207, 6077470, 14053561, 32497507, 75147355, 173771026, 401828790, 929190453, 2148663614, 4968578109, 11489359399, 26568039511, 61436038272

Offset: 1

Author

R. H. Hardin, Nov 08 2013

Keywords

• nonn

Comments

Column 2 of A231382.

Examples

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

Links

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

Crossrefs

Cf. A231382.

Formula

Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 2*a(n-3) - 2*a(n-4) - a(n-5) for n>6.

Empirical g.f.: x*(2 + 4*x - 5*x^2 + x^3 - 5*x^4 - 2*x^5) / (1 - 3*x + 2*x^2 - 2*x^3 + 2*x^4 + x^5). - Colin Barker, Mar 18 2018