A208071 Number of 6 X n 0..1 arrays avoiding 0 0 0 and 1 1 1 horizontally and 0 0 1 and 0 1 1 vertically.

16, 256, 324, 1764, 7056, 26244, 108900, 435600, 1726596, 6937956, 27751824, 110880900, 443776356, 1775105424, 7099410564, 28399664484, 113598657936, 454386542724, 1817562348900, 7270249395600, 29080932870276, 116323860905316

Offset

1,1

Comments

Row 6 of A208069.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 2*a(n-1) + 4*a(n-2) + 17*a(n-3) - 2*a(n-4) - 4*a(n-5) - 16*a(n-6) for n>8.

Empirical g.f.: 4*x*(4 + 56*x - 63*x^2 - 45*x^3 - 522*x^4 + 36*x^5 + 32*x^6 + 448*x^7) / ((1 - x)*(1 - 4*x)*(1 + x + x^2)*(1 + 2*x + 4*x^2)). - Colin Barker, Jun 27 2018

Example

Some solutions for n=4:
..0..1..0..1....1..0..1..1....1..0..0..1....0..0..1..1....1..0..0..1
..0..0..1..0....0..1..0..0....0..1..1..0....0..1..0..0....0..1..1..0
..0..1..0..1....0..0..1..1....1..0..0..1....0..0..1..1....1..0..0..1
..0..0..1..0....0..1..0..0....0..1..1..0....0..1..0..0....0..0..1..0
..0..1..0..0....0..0..1..0....1..0..0..1....0..0..1..1....1..0..0..1
..0..0..1..0....0..1..0..0....0..0..1..0....0..1..0..0....0..0..1..0

Crossrefs

Cf. A208069.

Sequence in context: A077412 A208498 A207586 * A206984 A207842 A135554

Adjacent sequences: A208068 A208069 A208070 * A208072 A208073 A208074

Keyword

nonn

Author

R. H. Hardin, Feb 23 2012

Status

approved