A297507 Number of 2 X n 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 1 or 2 neighboring 1s.

1, 10, 31, 68, 218, 729, 2097, 6139, 18932, 57273, 170792, 514608, 1554993, 4677797, 14071941, 42401182, 127713015, 384477424, 1157762858, 3486768241, 10499588277, 31616525407, 95208917296, 286707283257, 863361068252, 2599853035248

Offset: 1

Author

R. H. Hardin, Dec 31 2017

Keywords

• nonn

Examples

			Some solutions for n=7:
..1..0..0..1..1..0..0. .0..1..0..0..0..1..0. .1..0..0..0..0..0..0
..1..1..0..0..0..1..1. .1..0..1..0..0..1..1. .1..1..0..0..1..1..1
		

Links

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

Crossrefs

Row 2 of A297506.

Formula

Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 9*a(n-3) - 6*a(n-4) - 8*a(n-5).

Empirical g.f.: x*(1 + 7*x + 3*x^2 - 14*x^3 - 8*x^4) / (1 - 3*x + 2*x^2 - 9*x^3 + 6*x^4 + 8*x^5). - Colin Barker, Feb 28 2019