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A196316 Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 1,3,0,2,4 for x=0,1,2,3,4. 7
1, 7, 10, 23, 57, 122, 275, 623, 1394, 3133, 7045, 15824, 35557, 79901, 179530, 403401, 906439, 2036744, 4576523, 10283359, 23106492, 51919817, 116662775, 262138870, 589020695, 1323517493, 2973916806, 6682330407, 15015060135, 33738533866 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Every 0 is next to 0 1's, every 1 is next to 1 3's, every 2 is next to 2 0's, every 3 is next to 3 2's, every 4 is next to 4 4's.
Column 2 of A196322.
LINKS
FORMULA
Empirical: a(n) = a(n-1) +2*a(n-2) +2*a(n-3) -a(n-5).
Empirical g.f.: x*(1 + 6*x + x^2 - 3*x^3) / ((1 + x + x^2)*(1 - 2*x - x^2 + x^3)). - Colin Barker, Feb 18 2018
EXAMPLE
Some solutions for n=4:
..0..0....2..0....0..2....0..0....0..2....0..0....0..0....0..2....0..0....0..2
..0..2....0..2....2..0....0..0....0..0....0..0....0..2....0..0....2..2....0..0
..0..2....0..2....2..0....0..0....0..0....0..0....0..2....0..0....0..0....0..0
..2..0....0..0....0..2....0..2....0..2....2..0....0..0....0..0....2..0....2..0
CROSSREFS
Sequence in context: A103119 A054224 A183330 * A134329 A175492 A241052
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 01 2011
STATUS
approved

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Last modified April 21 19:32 EDT 2024. Contains 371885 sequences. (Running on oeis4.)