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A251337 Number of (n+1) X (2+1) 0..3 arrays with every 2 X 2 subblock summing to a nonzero multiple of 3. 1
455, 3315, 24714, 189129, 1487375, 12022920, 99776859, 848228679, 7364934770, 65097686685, 583829921739, 5297111776824, 48496766872295, 447087492211875, 4143325157339274, 38549110514055249, 359711119457800055 (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) = 27*a(n-1) - 252*a(n-2) + 813*a(n-3) + 589*a(n-4) - 5250*a(n-5) - 2310*a(n-6) + 1764*a(n-7).

Empirical g.f.: x*(455 - 8970*x + 49869*x^2 - 12684*x^3 - 354270*x^4 - 131964*x^5 + 112896*x^6) / ((1 - 6*x)*(1 - 7*x)*(1 - 6*x - 6*x^2)*(1 - 8*x - 14*x^2 + 7*x^3)). -  Colin Barker, Nov 29 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 2 of A251343.

Sequence in context: A324633 A260735 A241618 * A282232 A061544 A015276

Adjacent sequences:  A251334 A251335 A251336 * A251338 A251339 A251340

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 01 2014

STATUS

approved

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Last modified January 20 08:18 EST 2020. Contains 331081 sequences. (Running on oeis4.)