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A204679 Number of n X 2 0..3 arrays with no occurrence of three equal elements in a row horizontally, vertically, diagonally or antidiagonally, and new values 0..3 introduced in row major order. 3
2, 15, 159, 2191, 31168, 447343, 6427791, 92387812, 1327953799, 19087798375, 274365294336, 3943689122935, 56686048473223, 814797524429284, 11711788424726319, 168343648648695295, 2419748633865949120 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A204685.

LINKS

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

FORMULA

Empirical: a(n) = 14*a(n-1) +14*a(n-2) -124*a(n-3) -6*a(n-4) +90*a(n-5) -27*a(n-6) for n>8.

Empirical g.f.: x*(2 - 13*x - 79*x^2 + 3*x^3 + 140*x^4 - 57*x^5 - 21*x^6 + 9*x^7) / ((1 + x)*(1 + 3*x)*(1 - 3*x + x^2)*(1 - 15*x + 9*x^2)). - Colin Barker, Feb 23 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

CROSSREFS

Cf. A204685.

Sequence in context: A324463 A139085 A268070 * A259608 A317278 A140809

Adjacent sequences:  A204676 A204677 A204678 * A204680 A204681 A204682

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 18 2012

STATUS

approved

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Last modified May 23 07:08 EDT 2019. Contains 323508 sequences. (Running on oeis4.)