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A183476 Number of n X 2 0..2 arrays with every element equal to either the sum mod 3 of its vertical neighbors or the sum mod 3 of its horizontal neighbors. 1
3, 15, 39, 135, 495, 1647, 5751, 20223, 70119, 244863, 855927, 2985903, 10426887, 36416223, 127148535, 444006927, 1550518119, 5414352255, 18907098327, 66024403695, 230558764743, 805118884191, 2811503074743, 9817858453455 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A183483.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) + 12*a(n-3) - 18*a(n-4) - 36*a(n-6).

Empirical g.f.: 3*x*(1 + 2*x - 2*x^2 - 6*x^3 - 12*x^4 - 12*x^5) / ((1 - 6*x^3)*(1 - 3*x - 6*x^3)). - Colin Barker, Mar 29 2018

EXAMPLE

Some solutions for 4 X 2.

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

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

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

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

CROSSREFS

Cf. A183483.

Sequence in context: A065765 A318738 A146853 * A297621 A014309 A298049

Adjacent sequences:  A183473 A183474 A183475 * A183477 A183478 A183479

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 05 2011

STATUS

approved

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Last modified January 24 07:45 EST 2021. Contains 340398 sequences. (Running on oeis4.)