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A198908 Number of n X 2 0..7 arrays with values 0..7 introduced in row major order and no element equal to any horizontal or vertical neighbor. 3
1, 4, 34, 500, 10867, 313132, 10856948, 418689772, 17067989413, 715189507700, 30371156968582, 1298083132473604, 55654030558406039, 2389712969490386908, 102686352402421016536, 4414019789796312628796, 189771542890022982723145 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A198914.

LINKS

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

FORMULA

Empirical: a(n) = 88*a(n-1) - 2613*a(n-2) + 33232*a(n-3) - 184531*a(n-4) + 400344*a(n-5) - 246519*a(n-6).

Conjectures from Colin Barker, Feb 22 2018: (Start)

G.f.: x*(1 - 84*x + 2295*x^2 - 25272*x^3 + 107312*x^4 - 128772*x^5) / ((1 - x)*(1 - 3*x)*(1 - 7*x)*(1 - 13*x)*(1 - 21*x)*(1 - 43*x)).

a(n) = (1036945 + 344344*3^n + 75465*7^n + 12040*13^n + 2795*21^n + 91*43^n) / 2817360.

(End)

EXAMPLE

Some solutions with values 0 to 7 for n=5:

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

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

..4..5....4..2....3..4....4..5....4..5....4..5....4..5....4..5....4..5....4..5

..0..3....1..5....5..6....2..3....6..7....3..6....6..2....6..1....0..6....6..7

..6..7....6..7....2..7....6..7....7..1....7..3....2..7....5..7....7..1....2..4

CROSSREFS

Cf. A198914.

Sequence in context: A274244 A002105 A198717 * A207864 A222077 A081972

Adjacent sequences:  A198905 A198906 A198907 * A198909 A198910 A198911

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 31 2011

STATUS

approved

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Last modified May 20 17:41 EDT 2018. Contains 304340 sequences. (Running on oeis4.)