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A231376
Number of n X 2 0..1 arrays with no element less than a strict majority of its horizontal and vertical neighbors.
2
2, 10, 21, 48, 113, 261, 601, 1390, 3216, 7435, 17190, 39751, 91921, 212555, 491510, 1136570, 2628207, 6077470, 14053561, 32497507, 75147355, 173771026, 401828790, 929190453, 2148663614, 4968578109, 11489359399, 26568039511, 61436038272
OFFSET
1,1
COMMENTS
Column 2 of A231382.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 2*a(n-3) - 2*a(n-4) - a(n-5) for n>6.
Empirical g.f.: x*(2 + 4*x - 5*x^2 + x^3 - 5*x^4 - 2*x^5) / (1 - 3*x + 2*x^2 - 2*x^3 + 2*x^4 + x^5). - Colin Barker, Mar 18 2018
EXAMPLE
Some solutions for n=3:
..1..0....0..1....0..0....1..0....0..0....1..0....0..0....0..1....0..0....0..0
..1..0....0..0....1..1....0..0....0..0....1..0....0..1....0..1....0..0....1..1
..0..0....0..0....1..1....0..0....0..0....1..0....0..1....0..1....1..1....0..0
CROSSREFS
Cf. A231382.
Sequence in context: A294549 A294550 A296555 * A304700 A318548 A318210
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 08 2013
STATUS
approved