A297296 Number of n X 5 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 2 neighboring 1s.

1, 4, 9, 21, 49, 114, 266, 620, 1446, 3372, 7864, 18340, 42772, 99752, 232640, 542560, 1265352, 2951040, 6882384, 16051024, 37434032, 87303264, 203607776, 474851968, 1107444896, 2582771648, 6023513600, 14047976768, 32762547648, 76408478336

Offset: 1

Author

R. H. Hardin, Dec 27 2017

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 5 of A297299.

Formula

Empirical: a(n) = 2*a(n-1) + 2*a(n-2) - 2*a(n-3) - 2*a(n-4) for n>5.

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