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URL: https://oeis.org/A183315

⇱ A183315 - OEIS

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A183315
Number of n X 3 binary arrays with an element zero only if there are an even number of ones to its left and an even number of ones above it.
1
5, 13, 43, 124, 377, 1109, 3305, 9767, 28959, 85677, 253693, 750777, 2222308, 6577131, 19466625, 57614249, 170519517, 504678557, 1493676557, 4420766649, 13083945331, 38723960052, 114609540289, 339204648201, 1003928499625
OFFSET
1,1
COMMENTS
Column 3 of A183322.
LINKS
FORMULA
Empirical: a(n) = a(n-1) + 9*a(n-2) - 3*a(n-3) - 21*a(n-4) + a(n-5) + 13*a(n-6) + a(n-7) - a(n-8).
Empirical g.f.: x*(5 + 8*x - 15*x^2 - 21*x^3 + 10*x^4 + 13*x^5 - x^7) / (1 - x - 9*x^2 + 3*x^3 + 21*x^4 - x^5 - 13*x^6 - x^7 + x^8). - Colin Barker, Mar 27 2018
EXAMPLE
Some solutions for 5 X 3:
..1..1..1....0..1..1....1..1..0....1..1..0....1..1..0....1..1..1....1..1..0
..1..1..1....1..1..1....1..1..0....1..1..0....1..1..1....1..1..1....1..1..1
..0..0..0....1..1..1....0..0..0....0..1..1....1..1..1....0..0..0....0..0..1
..0..1..1....0..1..1....0..0..0....0..1..1....1..1..0....1..1..0....0..0..1
..0..1..1....0..0..1....0..1..1....0..0..1....1..1..0....1..1..1....0..1..1
CROSSREFS
Cf. A183322.
Sequence in context: A093576 A147259 A328740 * A391990 A183184 A115785
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 03 2011
STATUS
approved