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A195972 Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,0,1,3,4 for x=0,1,2,3,4. 1
3, 9, 14, 23, 43, 78, 139, 249, 450, 815, 1475, 2674, 4859, 8841, 16102, 29359, 53587, 97894, 178971, 327425, 599394, 1097871, 2011875, 3688402, 6764595, 12410585, 22775742, 41808791, 76765147, 140977582, 258949451, 475718009, 874068802 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Every 0 is next to 0 2's, every 1 is next to 1 0's, every 2 is next to 2 1's, every 3 is next to 3 3's, every 4 is next to 4 4's.
Column 2 of A195978.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) +a(n-3) -a(n-4) -2*a(n-5) -2*a(n-6) -a(n-7).
Empirical g.f.: x*(1 + x)^2*(3 - 3*x - x^2 - 3*x^3 - 2*x^4) / ((1 + x^2)*(1 - x - x^2)*(1 - x - x^2 - x^3)). - Colin Barker, May 08 2018
EXAMPLE
Some solutions for n=4:
..0..1....2..1....1..1....1..0....0..1....1..0....1..2....0..1....0..0....0..1
..1..1....1..0....0..0....1..0....1..1....1..0....0..1....0..1....0..0....0..1
..1..0....1..0....0..0....1..0....1..0....1..1....0..1....1..1....0..0....0..1
..1..0....2..1....1..1....1..0....2..1....0..1....1..2....1..0....0..0....0..1
CROSSREFS
Cf. A195978.
Sequence in context: A111907 A309149 A294480 * A274435 A136562 A305342
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 25 2011
STATUS
approved

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Last modified July 23 04:10 EDT 2024. Contains 374544 sequences. (Running on oeis4.)