A269054 Number of 3 X n 0..2 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once.

27, 174, 594, 3078, 13140, 58752, 253416, 1090344, 4637904, 19604352, 82332384, 343986912, 1430547456, 5925418752, 24456120000, 100618925568, 412797979584, 1689208728576, 6896384506176, 28095875422848, 114241910041536

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - a(n-2) - 28*a(n-3) - 4*a(n-4) + 16*a(n-5) - 4*a(n-6) for n>8.

Empirical g.f.: 3*x*(9 + 4*x - 141*x^2 + 148*x^3 + 82*x^4 - 38*x^5 - 24*x^6 + 8*x^7) / (1 - 3*x - 4*x^2 + 2*x^3)^2. - Colin Barker, Jan 18 2019

Example

Some solutions for n=4:
..2..2..1..1. .0..1..2..2. .0..1..0..1. .2..2..1..2. .1..1..2..1
..2..2..2..2. .0..1..0..1. .0..0..0..1. .2..2..1..2. .2..2..2..2
..1..2..1..2. .2..1..2..1. .1..1..0..0. .2..2..2..1. .1..2..1..2

Crossrefs

Row 3 of A269052.

Sequence in context: A372444 A174617 A055339 * A248234 A083560 A125337

Adjacent sequences: A269051 A269052 A269053 * A269055 A269056 A269057

Keyword

nonn

Author

R. H. Hardin, Feb 18 2016

Status

approved