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A183355 One quarter the number of nX3 1..4 arrays with no two neighbors of any element equal to each other 1
12, 144, 432, 1296, 3888, 11664, 34992, 104976, 314928, 944784, 2834352, 8503056, 25509168, 76527504, 229582512, 688747536, 2066242608, 6198727824, 18596183472, 55788550416, 167365651248, 502096953744, 1506290861232, 4518872583696 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A183362

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

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

EXAMPLE

Some solutions for 5X3 with a(1,1)=1

..1..1..4....1..1..2....1..4..2....1..2..4....1..1..4....1..3..3....1..2..4

..4..2..2....2..4..3....1..3..2....4..2..1....3..2..4....2..4..1....1..2..4

..3..3..1....2..4..3....2..3..4....4..3..3....3..2..1....2..4..1....3..3..1

..2..4..4....1..1..2....2..1..4....2..1..4....4..4..3....1..3..2....2..4..1

..1..1..3....4..3..2....4..1..3....3..1..4....2..1..3....1..3..2....1..4..2

CROSSREFS

Sequence in context: A207370 A208015 A208557 * A267716 A207309 A207115

Adjacent sequences:  A183352 A183353 A183354 * A183356 A183357 A183358

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 04 2011

STATUS

approved

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Last modified January 25 16:01 EST 2022. Contains 350572 sequences. (Running on oeis4.)