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A233157 Number of 4 X n 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally or antidiagonally. 1
81, 384, 2592, 17496, 121176, 842616, 5871528, 40931568, 285366888, 1989557640, 13871104848, 96708780360, 674249796360, 4700843090928, 32774093555112, 228499694410248, 1593090904911120, 11106967289377032, 77437340197187976 (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) = 9*a(n-1) - 15*a(n-2) + 6*a(n-3) for n>7.

Empirical g.f.: 3*x*(27 - 115*x + 117*x^2 - 186*x^3 + 96*x^4 - 360*x^5 + 216*x^6) / (1 - 9*x + 15*x^2 - 6*x^3). - Colin Barker, Oct 09 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

CROSSREFS

Row 4 of A233155.

Sequence in context: A205737 A236035 A236028 * A237108 A237101 A236618

Adjacent sequences:  A233154 A233155 A233156 * A233158 A233159 A233160

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 05 2013

STATUS

approved

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Last modified June 19 06:47 EDT 2019. Contains 324218 sequences. (Running on oeis4.)