A278281 Number of 2 X n 0..1 arrays with every element both equal and not equal to some elements at offset (-1,-1) (-1,0) (-1,1) (0,-1) (0,1) or (1,0), with upper left element zero.

0, 2, 4, 13, 36, 109, 317, 938, 2754, 8114, 23869, 70264, 206775, 608587, 1791104, 5271458, 15514416, 45660689, 134384272, 395507653, 1164021849, 3425843074, 10082628314, 29674271654, 87334607025, 257035243772, 756482665279

Offset

1,2

Links

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

Formula

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

Empirical g.f.: x^2*(2 - x^2) / (1 - 2*x - 3*x^2 + x^3 - x^4). - Colin Barker, Feb 09 2019

Example

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

Crossrefs

Row 2 of A278280.

Sequence in context: A148236 A148237 A148238 * A148239 A148240 A151354

Adjacent sequences: A278278 A278279 A278280 * A278282 A278283 A278284

Keyword

nonn

Author

R. H. Hardin, Nov 16 2016

Status

approved