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A275222 Number of n X 2 0..2 arrays with no element equal to any value at offset (-2,-1) (-2,1) or (-1,0) and new values introduced in order 0..2. 1
2, 6, 11, 27, 66, 162, 404, 1007, 2512, 6271, 15655, 39084, 97580, 243626, 608259, 1518638, 3791579, 9466427, 23634810, 59008986, 147327628, 367832623, 918367048, 2292885359, 5724642759, 14292705300, 35684571668, 89093606034, 222439846275 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

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

Empirical g.f.: x*(1 + x - x^2)*(2 - 2*x - x^2 - x^3) / ((1 - x)*(1 - 2*x - x^2 - x^3 + x^4)). - Colin Barker, Feb 01 2019

EXAMPLE

Some solutions for n=4:

..0..1. .0..0. .0..1. .0..1. .0..1. .0..1. .0..0. .0..1. .0..1. .0..1

..1..0. .1..2. .1..0. .1..0. .2..0. .1..0. .1..2. .1..2. .1..0. .2..0

..2..2. .2..1. .0..2. .2..1. .0..2. .0..1. .2..1. .2..1. .0..2. .0..1

..1..0. .1..2. .2..0. .1..2. .1..1. .1..2. .0..0. .1..2. .1..0. .2..0

CROSSREFS

Column 2 of A275228.

Sequence in context: A091622 A191315 A184884 * A165821 A296390 A135048

Adjacent sequences:  A275219 A275220 A275221 * A275223 A275224 A275225

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jul 20 2016

STATUS

approved

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Last modified May 24 06:53 EDT 2019. Contains 323529 sequences. (Running on oeis4.)