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A231377
Number of n X 3 0..1 arrays with no element less than a strict majority of its horizontal and vertical neighbors.
1
4, 21, 93, 378, 1519, 6126, 24747, 99964, 403743, 1630662, 6586087, 26600572, 107437031, 433927396, 1752589551, 7078534592, 28589495207, 115470119764, 466372299261, 1883631211124, 7607798625811, 30727139997676, 124103854340837
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 16*a(n-3) - 14*a(n-4) - 3*a(n-5) + 8*a(n-6) - 9*a(n-7) - 2*a(n-8) + 6*a(n-9) + 2*a(n-10) for n>11.
Empirical g.f.: x*(4 - 3*x + 11*x^2 - 13*x^3 - 6*x^4 - 12*x^5 - 15*x^6 + 3*x^7 + 13*x^8 + 8*x^9 + 2*x^10) / (1 - 6*x + 11*x^2 - 16*x^3 + 14*x^4 + 3*x^5 - 8*x^6 + 9*x^7 + 2*x^8 - 6*x^9 - 2*x^10). - Colin Barker, Sep 28 2018
EXAMPLE
Some solutions for n=3:
..0..0..0....1..0..0....0..0..0....0..0..1....1..1..0....0..1..0....0..1..1
..1..0..1....0..0..0....0..0..1....0..0..0....1..1..0....0..0..0....0..0..1
..1..0..0....0..0..1....0..0..1....0..0..0....0..0..0....0..1..0....0..0..0
CROSSREFS
Column 3 of A231382.
Sequence in context: A328345 A371309 A220574 * A017967 A292308 A076901
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 08 2013
STATUS
approved