A297300 Number of 3 X n 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 2 neighboring 1s.

1, 1, 3, 5, 9, 17, 32, 60, 113, 213, 401, 755, 1422, 2678, 5043, 9497, 17885, 33681, 63428, 119448, 224945, 423617, 797757, 1502339, 2829210, 5327978, 10033667, 18895437, 35583953, 67011825, 126196904, 237654452, 447551697, 842830925

Offset: 1

Author

R. H. Hardin, Dec 27 2017

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Row 3 of A297299.

Formula

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

Empirical g.f.: x*(1 - x)*(1 + x^2)^2 / (1 - 2*x + x^2 - 2*x^3 + x^4). - Colin Barker, Feb 26 2019