A274729 - OEIS

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

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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