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A232923 Number of 4 X n 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally, diagonally or antidiagonally. 1
81, 162, 1122, 5808, 33702, 186720, 1054446, 5907444, 33206862, 186398988, 1046931522, 5878727460, 33013750890, 185390166264, 1041086668026, 5846332684128, 32830815650766, 184365298149288, 1035325615443174 (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) + 16*a(n-2) - 3*a(n-3) - 25*a(n-4) + 2*a(n-5) + 4*a(n-6) for n>7.

Empirical g.f.: 3*x*(27 - 27*x - 220*x^2 + 31*x^3 + 279*x^4 - 20*x^5 - 40*x^6) / (1 - 3*x - 16*x^2 + 3*x^3 + 25*x^4 - 2*x^5 - 4*x^6). - Colin Barker, Oct 06 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

CROSSREFS

Row 4 of A232920.

Sequence in context: A031494 A043324 A267696 * A250655 A184003 A183995

Adjacent sequences:  A232920 A232921 A232922 * A232924 A232925 A232926

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 02 2013

STATUS

approved

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Last modified December 17 14:12 EST 2018. Contains 318201 sequences. (Running on oeis4.)