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A232901
Number of (n+1) X (1+1) 0..2 arrays with every element next to itself plus and minus one within the range 0..2 horizontally or antidiagonally.
1
0, 4, 8, 12, 32, 84, 184, 412, 976, 2276, 5224, 12076, 28032, 64884, 150040, 347324, 804144, 1861124, 4307400, 9970252, 23077600, 53414548, 123632504, 286160860, 662347408, 1533063972, 3548423976, 8213173612, 19010179136, 44000880564
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) - a(n-2) + 4*a(n-3).
Empirical g.f.: 4*x^2 / (1 - 2*x + x^2 - 4*x^3). - Colin Barker, Oct 06 2018
EXAMPLE
Some solutions for n=5:
..2..1....0..1....2..1....0..1....2..1....2..1....0..1....0..1....2..1....0..1
..0..2....2..0....0..2....2..2....0..0....0..0....2..1....2..1....0..2....2..1
..1..0....1..2....1..0....1..0....1..2....1..2....0..0....0..1....1..0....0..1
..2..1....0..1....0..1....0..1....0..1....2..1....1..2....2..1....1..2....2..0
..0..2....2..2....2..0....2..2....2..2....0..2....1..0....0..0....1..0....1..2
..1..0....1..0....1..2....1..0....1..0....1..0....1..2....1..2....1..2....1..0
CROSSREFS
Column 1 of A232908.
Sequence in context: A370134 A035403 A050908 * A038563 A083492 A137337
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 02 2013
STATUS
approved