A275267 Number of 3 X n 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.

5, 24, 128, 688, 3728, 20224, 109760, 595744, 3233600, 17551552, 95267648, 517101184, 2806762496, 15234766720, 82692468224, 448844700928, 2436274668800, 13223803801600, 71777205266432, 389597975982592, 2114690622553088

Offset

1,1

Links

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

Formula

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

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

Example

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

Crossrefs

Row 3 of A275266.

Sequence in context: A006326 A058120 A271544 * A278679 A000349 A327118

Adjacent sequences: A275264 A275265 A275266 * A275268 A275269 A275270

Keyword

nonn

Author

R. H. Hardin, Jul 21 2016

Status

approved