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A230470 Number of 2 X n 0..2 arrays x(i,j) with each element horizontally, diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 3, and upper left element zero. 1
0, 0, 0, 36, 216, 1260, 6912, 38340, 213192, 1188252, 6624720, 36934452, 205906968, 1147892364, 6399246240, 35674383780, 198876914280, 1108695761532, 6180739391088, 34456287198996, 192086358160824, 1070839950246252 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) - a(n-2) - 12*a(n-3) + 20*a(n-4) + 24*a(n-5).
Empirical g.f.: 36*x^3 / ((1 + x)*(1 - 7*x + 8*x^2 + 4*x^3 - 24*x^4)). - Colin Barker, Sep 21 2018
EXAMPLE
Some solutions for n=4:
..0..1..2..0....0..0..1..0....0..1..0..0....0..1..1..0....0..2..2..0
..0..2..1..0....2..1..0..2....2..0..1..2....1..2..2..0....0..1..1..1
CROSSREFS
Row 2 of A230469.
Sequence in context: A232677 A232670 A365308 * A066610 A176696 A269031
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 20 2013
STATUS
approved

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Last modified July 16 08:10 EDT 2024. Contains 374345 sequences. (Running on oeis4.)