A183444 Number of n X 3 binary arrays with every 1 having exactly two king-move neighbors equal to 1.

1, 9, 18, 30, 107, 265, 553, 1505, 3852, 8922, 22477, 56889, 137617, 340401, 851098, 2091618, 5160851, 12817517, 31655009, 78159377, 193558964, 478614470, 1182673261, 2925763109, 7235864705, 17887850273, 44237338898, 109401520982

Offset: 1

Author

R. H. Hardin, Jan 04 2011

Keywords

• nonn

Comments

Column 3 of A183450.

Examples

			Some solutions for 5 X 3:
..0..1..0....1..1..0....0..0..0....0..0..0....1..1..0....0..0..0....0..0..1
..0..1..1....1..0..0....0..1..1....0..1..0....0..1..0....0..0..0....0..1..1
..0..0..0....0..0..0....0..0..1....1..0..1....0..0..0....0..0..0....0..0..0
..0..1..0....0..1..1....1..0..0....1..0..1....1..0..0....1..1..0....1..0..0
..1..1..0....0..0..1....1..1..0....0..1..0....1..1..0....1..0..0....1..1..0
		

Links

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

Crossrefs

Cf. A183450.

Formula

Empirical: a(n) = 2*a(n-1) - a(n-2) + 8*a(n-3) - 7*a(n-4) + 2*a(n-5) - 2*a(n-6).

Empirical g.f.: x*(1 + 7*x + x^2 - 5*x^3 - 2*x^5) / (1 - 2*x + x^2 - 8*x^3 + 7*x^4 - 2*x^5 + 2*x^6). - Colin Barker, Feb 27 2018