A228684 Number of 3 X n binary arrays with no two ones adjacent horizontally, diagonally or antidiagonally.

8, 17, 77, 216, 809, 2529, 8832, 28793, 97933, 324464, 1092561, 3642241, 12217528, 40825697, 136745357, 457357256, 1531058169, 5122533089, 17144628912, 57369165513, 191993439053, 642478726624, 2150072260001, 7195049684481

Offset: 1

Author

R. H. Hardin, Aug 30 2013

Keywords

• nonn

Examples

			Some solutions for n=4:
..0..0..0..1....0..0..0..0....0..0..0..0....1..0..1..0....0..1..0..0
..1..0..0..0....1..0..1..0....0..1..0..0....1..0..0..0....0..0..0..0
..1..0..1..0....0..0..0..0....0..0..0..1....0..0..0..1....1..0..1..0
		

Links

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

Crossrefs

Row 3 of A228683.

Formula

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

Empirical g.f.: x*(8 + x - 5*x^2) / (1 - 2*x - 6*x^2 + 5*x^3). - Colin Barker, Sep 12 2018