A275260 Number of n X 2 0..2 arrays with no element equal to any value at offset (-2,-1) (-2,1) or (-1,-1) and new values introduced in order 0..2.

2, 9, 24, 64, 172, 476, 1320, 3672, 10220, 28472, 79376, 221320, 617160, 1720976, 4799104, 13382832, 37319536, 104069760, 290210016, 809282592, 2256773088, 6293258240, 17549436800, 48938515904, 136470379968, 380562509568

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - 6*a(n-3) + 6*a(n-4) + 4*a(n-5) - 16*a(n-6) + 12*a(n-7) + 8*a(n-8) - 8*a(n-9) for n>10.

Empirical g.f.: x*(2 + x - 8*x^2 - 2*x^3 + 6*x^4 - 2*x^5 - 4*x^6 + 16*x^7 - 8*x^9) / (1 - 4*x + 2*x^2 + 6*x^3 - 6*x^4 - 4*x^5 + 16*x^6 - 12*x^7 - 8*x^8 + 8*x^9). - Colin Barker, Feb 02 2019

Example

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

Crossrefs

Column 2 of A275266.

Sequence in context: A356114 A079997 A351252 * A248436 A354016 A222667

Adjacent sequences: A275257 A275258 A275259 * A275261 A275262 A275263

Keyword

nonn

Author

R. H. Hardin, Jul 21 2016

Status

approved