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A274723 Number of n X 3 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. 1
5, 24, 68, 260, 1040, 4132, 16524, 66088, 264332, 1057316, 4229264, 16917028, 67668108, 270672424, 1082689676, 4330758692, 17323034768, 69292139044, 277168556172, 1108674224680, 4434696898700, 17738787594788, 70955150379152 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

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

Empirical g.f.: x*(5 + 9*x - 24*x^2 - 45*x^3 - 21*x^4 - 4*x^5 + 8*x^6) / ((1 - x)*(1 + x)*(1 - 4*x)*(1 + x + x^2)). - Colin Barker, Jan 30 2019

EXAMPLE

Some solutions for n=4:

..0..1..0. .0..0..0. .0..1..0. .0..1..0. .0..1..0. .0..1..0. .0..1..0

..1..0..1. .1..1..1. .1..0..1. .2..0..2. .2..0..2. .1..2..1. .1..2..1

..0..1..2. .2..2..2. .2..1..0. .0..1..0. .1..2..0. .2..1..2. .2..1..2

..1..2..1. .0..0..0. .0..0..1. .2..0..2. .0..0..2. .0..2..0. .1..0..1

CROSSREFS

Column 3 of A274728.

Sequence in context: A258290 A205669 A101147 * A006328 A213766 A000347

Adjacent sequences:  A274720 A274721 A274722 * A274724 A274725 A274726

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jul 03 2016

STATUS

approved

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Last modified May 22 00:02 EDT 2022. Contains 353931 sequences. (Running on oeis4.)