A269070 Number of n X 3 binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once.

7, 27, 123, 537, 2343, 10167, 43959, 189465, 814359, 3491691, 14937987, 63778065, 271799175, 1156345287, 4911870063, 20834207313, 88251723687, 373358554971, 1577691954507, 6659543294313, 28081651307943, 118299768626103

Offset

1,1

Links

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

Formula

Empirical: a(n) = 10*a(n-1) - 31*a(n-2) + 24*a(n-3) + 21*a(n-4) - 18*a(n-5) - 9*a(n-6).

Empirical g.f.: x*(7 - 43*x + 70*x^2 - 24*x^3 - 9*x^4 - 9*x^5) / (1 - 5*x + 3*x^2 + 3*x^3)^2. - Colin Barker, Jan 18 2019

Example

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

Crossrefs

Column 3 of A269075.

Sequence in context: A118101 A201380 A327623 * A147996 A267365 A034536

Adjacent sequences: A269067 A269068 A269069 * A269071 A269072 A269073

Keyword

nonn

Author

R. H. Hardin, Feb 19 2016

Status

approved