A269084 Number of n X 3 binary arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two not more than once.

7, 30, 114, 428, 1531, 5387, 18590, 63347, 213490, 713237, 2365217, 7794642, 25549763, 83359179, 270860625, 876943006, 2830104798, 9107202178, 29230933367, 93601324315, 299085155918, 953808773503, 3036347307176, 9649992762591

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 9*a(n-2) - 2*a(n-3) - 33*a(n-4) - 42*a(n-5) - 14*a(n-6) + 10*a(n-7) + 8*a(n-8) - a(n-10).

Empirical g.f.: x*(7 + 16*x - 9*x^2 - 56*x^3 - 60*x^4 - 15*x^5 + 13*x^6 + 8*x^7 - x^8 - x^9) / ((1 + x)^2*(1 - 2*x - 3*x^2 - x^3 + x^4)^2). - Colin Barker, Jan 19 2019

Example

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

Crossrefs

Column 3 of A269089.

Sequence in context: A368528 A085277 A375995 * A055269 A026631 A037709

Adjacent sequences: A269081 A269082 A269083 * A269085 A269086 A269087

Keyword

nonn

Author

R. H. Hardin, Feb 19 2016

Status

approved