A274729 Number of 4 X n 0..2 arrays with no element equal to any value at offset (-1,-2) (-2,-1) or (-1,0) and new values introduced in order 0..2.

4, 48, 260, 1632, 10368, 66132, 421904, 2691884, 17175124, 109583308, 699179884, 4461012792, 28462825592, 181602806300, 1158689573772, 7392845715224, 47168947581908, 300954422923484, 1920194732348424, 12251515609312728

Offset

1,1

Links

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

Formula

Empirical: a(n) = 8*a(n-1) - 10*a(n-2) - 4*a(n-3) + 13*a(n-4) - 7*a(n-5) + a(n-6) for n>7.

Empirical g.f.: 4*x*(1 + 4*x - 21*x^2 + 12*x^3 + 13*x^4 - 12*x^5 + 2*x^6) / ((1 - x)*(1 - 7*x + 3*x^2 + 7*x^3 - 6*x^4 + x^5)). - Colin Barker, Jan 30 2019

Example

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

Crossrefs

Row 4 of A274728.

Sequence in context: A275138 A273767 A292074 * A217153 A129002 A291623

Adjacent sequences: A274726 A274727 A274728 * A274730 A274731 A274732

Keyword

nonn

Author

R. H. Hardin, Jul 03 2016

Status

approved