login
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
OFFSET
1,1
LINKS
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: A362051 A191315 A184884 * A165821 A365046 A296390
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 20 2016
STATUS
approved