A183364 Number of n X 2 binary arrays with no element equal to the sum mod 3 of its horizontal and vertical neighbors.

2, 3, 5, 12, 21, 41, 84, 171, 355, 732, 1517, 3165, 6608, 13809, 28871, 60398, 126425, 264681, 554188, 1160473, 2430233, 5089614, 10659415, 22324873, 46757436, 97930229, 205109405, 429591772, 899761459, 1884515059, 3947047760, 8266953369

Offset: 1

Author

R. H. Hardin, Jan 04 2011

Keywords

• nonn

Comments

Column 2 of A183368.

Examples

			Some solutions for 5 X 2:
..0..0....1..0....0..1....0..1....0..0....1..1....1..1....0..1....1..0....1..1
..1..1....0..0....0..0....1..0....1..1....1..1....1..1....1..0....0..0....1..1
..1..1....1..1....1..1....0..0....1..1....1..1....0..0....0..0....0..1....1..1
..0..0....1..1....1..1....0..1....1..1....1..1....1..0....1..1....0..0....0..0
..1..0....1..1....1..1....1..0....1..1....0..0....0..1....1..1....1..0....1..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A183368.

Formula

Empirical: a(n) = 2*a(n-1) + a(n-3) - 4*a(n-6) - 3*a(n-7) + a(n-10).

Empirical g.f.: x*(1 + x)*(2 - 3*x + 2*x^2 - 2*x^3 - 4*x^4 - 2*x^5 + x^8) / (1 - 2*x - x^3 + 4*x^6 + 3*x^7 - x^10). - Colin Barker, Mar 28 2018