A207896 Number of 3 X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 0 and 1 1 1 vertically.

6, 36, 84, 198, 462, 1080, 2520, 5886, 13746, 32100, 74964, 175062, 408822, 954720, 2229552, 5206662, 12159090, 28395060, 66310836, 154855350, 361632894, 844519416, 1972201800, 4605672606, 10755603282, 25117504404, 58656777396

Offset

1,1

Comments

Row 3 of A207895.

Links

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

Formula

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

Empirical g.f.: 6*x*(1 + 5*x + 6*x^2 + 5*x^3 + 3*x^4 + 2*x^5) / (1 - x - 2*x^2 - 2*x^3 - x^4 - x^5). - Colin Barker, Jun 26 2018

Example

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

Crossrefs

Cf. A207895.

Sequence in context: A207763 A207347 A207769 * A207656 A207341 A152746

Adjacent sequences: A207893 A207894 A207895 * A207897 A207898 A207899

Keyword

nonn

Author

R. H. Hardin, Feb 21 2012

Status

approved