A274896 Number of 4 X n 0..2 arrays with no element equal to any value at offset (0,-1) (-1,-1) or (-2,0) and new values introduced in order 0..2.

6, 14, 38, 104, 290, 815, 2291, 6434, 18065, 50729, 142469, 400121, 1123718, 3155882, 8863073, 24891350, 69905726, 196325636, 551367590, 1548479459, 4348802339, 12213324374, 34300315505, 96330172385, 270536931545, 759785117405

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(6 - 16*x + 22*x^2 - 20*x^3 + 8*x^4 - x^5) / ((1 - x)*(1 - 4*x + 5*x^2 - 5*x^3 + x^4)). - Colin Barker, Jan 31 2019

Example

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

Crossrefs

Row 4 of A274895.

Sequence in context: A271459 A271010 A272579 * A330832 A134259 A069166

Adjacent sequences: A274893 A274894 A274895 * A274897 A274898 A274899

Keyword

nonn

Author

R. H. Hardin, Jul 10 2016

Status

approved