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A231248 Number of 3 X n 0..3 arrays x(i,j) with each element horizontally, diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero. 1
0, 6, 78, 464, 3090, 22460, 162766, 1169472, 8396770, 60331460, 433549110, 3115381720, 22385974490, 160857679996, 1155868628526, 8305679220784, 59681777605042, 428852885779252, 3081590524869798, 22143258241832392 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = 7*a(n-1) - 3*a(n-2) + 27*a(n-3) + 28*a(n-4) + 14*a(n-5) - 8*a(n-6) - 8*a(n-7) for n>8.
Empirical g.f.: 2*x^2*(3 + 18*x - 32*x^2 - 43*x^3 - 26*x^4 + 10*x^5 + 12*x^6) / (1 - 7*x + 3*x^2 - 27*x^3 - 28*x^4 - 14*x^5 + 8*x^6 + 8*x^7). - Colin Barker, Sep 28 2018
EXAMPLE
Some solutions for n=4:
..0..1..0..1....0..3..2..1....0..3..2..1....0..1..2..1....0..3..0..3
..2..3..2..1....0..1..0..1....2..1..0..1....2..3..2..3....2..1..2..1
..0..1..0..3....2..3..2..1....0..3..2..3....0..1..0..1....0..1..0..3
CROSSREFS
Row 3 of A231246.
Sequence in context: A134788 A167498 A250388 * A160240 A069669 A145359
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 06 2013
STATUS
approved

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Last modified July 24 12:16 EDT 2024. Contains 374583 sequences. (Running on oeis4.)