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A275038 Number of 3 X n 0..2 arrays with no element equal to any value at offset (0,-1) (-1,-2) or (-2,0) and new values introduced in order 0..2. 1
3, 18, 46, 137, 401, 1152, 3336, 9720, 28277, 82174, 238829, 694135, 2017380, 5863430, 17042197, 49533046, 143966504, 418434888, 1216170841, 3534771986, 10273734201, 29860375290, 86788495974, 252248762928, 733155217213 (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) = 3*a(n-1) - 2*a(n-2) + 4*a(n-3) + a(n-4) + 3*a(n-5) + 8*a(n-6) + a(n-7) - 3*a(n-8) - a(n-9) for n>10.

Empirical g.f.: x*(3 + 9*x - 2*x^2 + 23*x^3 + 7*x^4 + 12*x^5 + 10*x^6 - 10*x^7 - 8*x^8 - x^9) / (1 - 3*x + 2*x^2 - 4*x^3 - x^4 - 3*x^5 - 8*x^6 - x^7 + 3*x^8 + x^9). - Colin Barker, Jan 31 2019

EXAMPLE

Some solutions for n=4:

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

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

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

CROSSREFS

Row 3 of A275037.

Sequence in context: A337921 A094159 A138976 * A304976 A064043 A267639

Adjacent sequences:  A275035 A275036 A275037 * A275039 A275040 A275041

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jul 14 2016

STATUS

approved

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Last modified January 25 15:17 EST 2022. Contains 350572 sequences. (Running on oeis4.)