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A231295
Number of (n+1) X (1+1) 0..2 arrays with no element unequal to a strict majority of its horizontal, vertical and antidiagonal neighbors, with values 0..2 introduced in row major order.
1
1, 2, 4, 12, 32, 92, 264, 756, 2176, 6252, 17976, 51684, 148592, 427228, 1228328, 3531604, 10153824, 29193548, 83935256, 241324740, 693839952, 1994879932, 5735538696, 16490418228, 47412092736, 136315920428, 391925964280
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) + 3*a(n-2) - 4*a(n-4).
Empirical g.f.: x*(1 + x)^2*(1 - 2*x) / ((1 - x)*(1 - x - 4*x^2 - 4*x^3)). - Colin Barker, Sep 28 2018
EXAMPLE
Some solutions for n=4:
..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0
..0..0....0..0....0..1....0..1....0..1....0..0....0..0....0..0....0..0....0..0
..0..1....1..1....1..1....1..1....1..1....0..0....1..1....1..1....0..0....0..0
..1..1....1..1....0..0....2..2....1..1....0..1....1..2....1..0....1..1....0..0
..1..1....1..1....0..0....2..2....1..1....1..1....2..2....0..0....1..1....0..0
CROSSREFS
Column 1 of A231302.
Sequence in context: A152035 A026151 A025178 * A087211 A161177 A039721
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 07 2013
STATUS
approved