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

1,2

Links

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

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

Example

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

Crossrefs

Row 2 of A281205.

Sequence in context: A364764 A355864 A200039 * A189331 A157023 A101554

Adjacent sequences: A281203 A281204 A281205 * A281207 A281208 A281209

Keyword

nonn

Author

R. H. Hardin, Jan 17 2017

Status

approved