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A198710 Number of n X 3 0..3 arrays with values 0..3 introduced in row major order and no element equal to any horizontal or vertical neighbor. 2
2, 25, 401, 6548, 107042, 1749965, 28609241, 467717288, 7646461682, 125007943505, 2043688517681, 33411178843628, 546221629207922, 8929887496964645, 145989990956749721, 2386712874803449568, 39019101990629849762 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A198715.

LINKS

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

FORMULA

Empirical: a(n) = 19*a(n-1) - 45*a(n-2) + 27*a(n-3).

Empirical g.f.: x*(2 - 13*x + 16*x^2) / ((1 - x)*(1 - 18*x + 27*x^2)). - Colin Barker, Mar 02 2018

EXAMPLE

Some solutions with all values from 0 to 3 for n=4:

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

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

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

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

CROSSREFS

Cf. A198715.

Sequence in context: A085830 A270346 A212022 * A074209 A209467 A121252

Adjacent sequences:  A198707 A198708 A198709 * A198711 A198712 A198713

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 29 2011

STATUS

approved

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Last modified July 3 17:54 EDT 2022. Contains 355055 sequences. (Running on oeis4.)