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A207083
Number of n X 3 0..1 arrays avoiding 0 0 0 horizontally and 0 0 1 vertically.
1
7, 49, 241, 1117, 4891, 20953, 88465, 370753, 1546879, 6437929, 26754673, 111093277, 461065507, 1912995217, 7935844129, 32917778401, 136534855735, 566294540737, 2348729268913, 9741340873213, 40401894006955, 167564911503529
OFFSET
1,1
COMMENTS
Column 3 of A207088.
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) - 5*a(n-2) - 14*a(n-3) + 11*a(n-4) + 4*a(n-5) - a(n-6).
Empirical g.f.: x*(7 + 7*x - 18*x^2 + 14*x^3 + 3*x^4 - x^5) / ((1 - x)*(1 - 2*x - x^2)*(1 - 3*x - 5*x^2 + x^3)). - Colin Barker, Jun 18 2018
EXAMPLE
Some solutions for n=4:
..0..1..1....1..1..0....0..0..1....1..1..0....1..0..0....0..0..1....0..1..1
..1..1..0....0..0..1....0..1..1....1..0..1....1..0..1....1..0..0....0..1..1
..1..1..1....1..1..1....0..0..1....1..0..0....1..0..1....0..0..1....0..1..1
..1..0..1....1..0..0....0..0..1....0..0..1....1..0..1....0..0..1....0..1..1
CROSSREFS
Cf. A207088.
Sequence in context: A188768 A188757 A223947 * A207177 A207089 A375610
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 15 2012
STATUS
approved