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A199143 Number of nX2 0..3 arrays with values 0..3 introduced in row major order and each element equal to one or two horizontal and vertical neighbors 1
1, 3, 13, 65, 393, 2539, 16866, 113432, 766473, 5188597, 35148945, 238173743, 1614066774, 10938730576, 74134306725, 502428413393, 3405102418833, 23077383280435, 156402287318610, 1059984943413152, 7183834447992225 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A199149

LINKS

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

FORMULA

Empirical: a(n) = 7*a(n-1) +2*a(n-2) -16*a(n-3) -49*a(n-4) -35*a(n-5) +56*a(n-6) +54*a(n-7) +45*a(n-8) -27*a(n-9) for n>11

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A155867 A009102 A080227 * A002468 A198663 A156181

Adjacent sequences:  A199140 A199141 A199142 * A199144 A199145 A199146

KEYWORD

nonn

AUTHOR

R. H. Hardin Nov 03 2011

STATUS

approved

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Last modified August 5 22:41 EDT 2021. Contains 346488 sequences. (Running on oeis4.)