A301603 Number of nX3 0..1 arrays with every element equal to 0, 2 or 3 horizontally or vertically adjacent elements, with upper left element zero.

1, 2, 2, 8, 13, 26, 55, 154, 356, 884, 2161, 5440, 13511, 33780, 84398, 211338, 528999, 1325014, 3319005, 8315948, 20836784, 52214530, 130847203, 327910100, 821772985, 2059471558, 5161348174, 12935209836, 32417941793, 81245379630, 203616360639

Offset: 1

Author

R. H. Hardin, Mar 24 2018

Keywords

• nonn

Comments

Column 3 of A301608.

Examples

			Some solutions for n=5
..0..0..0. .0..0..1. .0..0..0. .0..1..1. .0..1..1. .0..0..0. .0..0..0
..0..0..0. .0..0..0. .0..1..0. .1..1..1. .1..1..1. .0..0..0. .0..1..0
..0..1..0. .0..1..0. .0..0..0. .1..0..1. .1..0..1. .0..1..0. .0..0..0
..0..0..0. .0..0..0. .0..1..0. .1..1..1. .1..1..1. .0..0..0. .1..1..1
..0..0..0. .0..0..0. .0..0..0. .0..1..1. .1..1..0. .1..0..0. .1..1..1
		

Links

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

Crossrefs

Cf. A301608.

Formula

Empirical: a(n) = a(n-1) +3*a(n-2) +4*a(n-3) +2*a(n-4) -8*a(n-5) -17*a(n-6) -19*a(n-7) -9*a(n-8) +6*a(n-9) +21*a(n-10) +15*a(n-11) +11*a(n-12) -2*a(n-13) -2*a(n-14) -4*a(n-15) -a(n-16) -a(n-17) +a(n-18)