A275184 Number of 4 X n 0..2 arrays with no element equal to any value at offset (-2,-1) (-1,0) or (-1,1) and new values introduced in order 0..2.

4, 12, 41, 141, 482, 1651, 5653, 19356, 66277, 226937, 777050, 2660679, 9110369, 31194604, 106812721, 365734965, 1252304626, 4287987275, 14682397949, 50273658876, 172140871373, 589423572097, 2018231606314, 6910580115135

Offset

1,1

Links

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

Formula

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

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

Example

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

Crossrefs

Row 4 of A275183.

Sequence in context: A002996 A076867 A308369 * A354338 A149341 A149342

Adjacent sequences: A275181 A275182 A275183 * A275185 A275186 A275187

Keyword

nonn

Author

R. H. Hardin, Jul 19 2016

Status

approved