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A208067
Number of n X 6 0..1 arrays avoiding 0 0 0 and 1 1 1 horizontally and 0 0 1 and 0 1 1 vertically.
1
26, 676, 2080, 6400, 12960, 26244, 44064, 73984, 111520, 168100, 236160, 331776, 443520, 592900, 763840, 984064, 1232064, 1542564, 1887840, 2310400, 2775520, 3334276, 3944160, 4665600, 5447520, 6360484, 7344064, 8479744, 9696960
OFFSET
1,1
COMMENTS
Column 6 of A208069.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) + 2*a(n-2) - 6*a(n-3) + 6*a(n-5) - 2*a(n-6) - 2*a(n-7) + a(n-8) for n>9.
Empirical g.f.: 2*x*(13 + 312*x + 338*x^2 + 522*x^3 + 28*x^4 - 76*x^5 + 26*x^6 + 26*x^7 - 13*x^8) / ((1 - x)^5*(1 + x)^3). - Colin Barker, Jun 27 2018
EXAMPLE
Some solutions for n=4:
..0..1..1..0..0..1....0..0..1..0..0..1....1..1..0..1..1..0....0..1..1..0..0..1
..1..0..0..1..1..0....1..1..0..0..1..0....1..0..1..1..0..1....1..0..0..1..1..0
..0..0..1..0..0..1....0..0..1..0..0..1....0..1..0..0..1..0....0..1..1..0..0..1
..1..0..0..1..0..0....0..1..0..0..1..0....1..0..1..0..0..1....1..0..0..1..0..0
CROSSREFS
Cf. A208069.
Sequence in context: A207843 A206985 A208377 * A207932 A207849 A208838
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 23 2012
STATUS
approved