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A231051 Number of 3Xn 0..3 arrays x(i,j) with each element horizontally, diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4 and at least one element with value (x(i,j)-1) mod 4, no adjacent elements equal, and upper left element zero 1
0, 2, 50, 128, 644, 5100, 33696, 211032, 1354848, 8755256, 56382600, 362808600, 2335743720, 15038803080, 96821412760, 623339871560, 4013124023592, 25836921761608, 166340644854200, 1070917308473608, 6894671429298216 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 3 of A231049

LINKS

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

FORMULA

Empirical: a(n) = 6*a(n-1) +18*a(n-3) +17*a(n-4) -98*a(n-5) -32*a(n-6) +6*a(n-7) -16*a(n-8) +36*a(n-9) -8*a(n-10) for n>11

EXAMPLE

Some solutions for n=4

..0..3..0..3....0..3..2..3....0..3..2..3....0..1..0..1....0..1..2..3

..2..1..2..1....2..1..0..3....2..1..0..1....0..3..2..1....2..3..0..3

..2..3..0..1....0..3..2..3....0..3..2..1....0..1..0..3....0..1..2..3

CROSSREFS

Sequence in context: A027619 A076267 A050800 * A317819 A231082 A318426

Adjacent sequences:  A231048 A231049 A231050 * A231052 A231053 A231054

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 03 2013

STATUS

approved

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Last modified November 15 14:06 EST 2019. Contains 329149 sequences. (Running on oeis4.)