A281206 Number of 2 X n 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.

0, 2, 14, 28, 52, 94, 166, 290, 502, 864, 1480, 2526, 4298, 7294, 12350, 20868, 35196, 59262, 99630, 167258, 280422, 469576, 785424, 1312318, 2190482, 3652854, 6086126, 10131820, 16853572, 28013854, 46531510, 77237906, 128126038, 212413104

Offset: 1

Author

R. H. Hardin, Jan 17 2017

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Row 2 of A281205.

Formula

Empirical: a(n) = 3*a(n-1) - a(n-2) - 3*a(n-3) + a(n-4) + a(n-5) for n>7.

Empirical g.f.: 2*x^2*(1 + 4*x - 6*x^2 - 6*x^3 + 3*x^4 + 2*x^5) / ((1 - x)*(1 - x - x^2)^2). - Colin Barker, Feb 18 2019