A302636 Number of 3Xn 0..1 arrays with every element equal to 0, 1, 3 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

4, 6, 8, 14, 25, 47, 83, 150, 269, 488, 876, 1581, 2845, 5133, 9242, 16661, 30012, 54094, 97457, 175631, 316451, 570258, 1027529, 1851592, 3336392, 6012049, 10833241, 19520945, 35175378, 63384029, 114213840, 205806518, 370850169, 668249367

Offset: 1

Author

R. H. Hardin, Apr 10 2018

Keywords

• nonn

Comments

Row 3 of A302635.

Examples

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

Links

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

Crossrefs

Cf. A302635.

Formula

Empirical: a(n) = a(n-1) +a(n-2) +2*a(n-4) -a(n-5) for n>7