A207559 Number of n X 3 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 1 1 and 1 1 0 vertically.

6, 36, 92, 221, 618, 1690, 4861, 13900, 40452, 117717, 345002, 1012682, 2983173, 8803252, 26036140, 77123437, 228815946, 679742490, 2021736365, 6019369820, 17938267476, 53500929061, 159681492682, 476893979146, 1425053001333

Offset

1,1

Comments

Column 3 of A207564.

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 6*a(n-2) - 21*a(n-3) + 36*a(n-4) + 12*a(n-5) - 39*a(n-6) + 6*a(n-7) + 10*a(n-8) - 3*a(n-9) for n>10.

Empirical g.f.: x*(6 - 88*x^2 + 11*x^3 + 384*x^4 - 128*x^5 - 440*x^6 + 160*x^7 + 120*x^8 - 45*x^9) / ((1 - x)*(1 + x)*(1 - 3*x)*(1 - 3*x + x^2)*(1 + x - x^2)*(1 - x - x^2)). - Colin Barker, Mar 05 2018

Example

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

Crossrefs

Cf. A207564.

Sequence in context: A213189 A080857 A108158 * A207414 A192278 A207106

Adjacent sequences: A207556 A207557 A207558 * A207560 A207561 A207562

Keyword

nonn

Author

R. H. Hardin, Feb 18 2012

Status

approved