A207747 Number of n X 3 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 0 1 and 1 0 0 vertically.

6, 36, 102, 270, 798, 2354, 7210, 22232, 69570, 218950, 693810, 2207142, 7047274, 22559004, 72371822, 232562110, 748347990, 2410664906, 7772348106, 25076879856, 80954866538, 261464311606, 844780530762, 2730274274910, 8826217794378

Offset

1,1

Comments

Column 3 of A207752.

Links

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

Formula

Empirical: a(n) = 7*a(n-1) - 9*a(n-2) - 32*a(n-3) + 72*a(n-4) + 36*a(n-5) - 147*a(n-6) + 9*a(n-7) + 109*a(n-8) - 28*a(n-9) - 24*a(n-10) + 8*a(n-11) for n>12. Corrected by Colin Barker, Mar 06 2018

Empirical g.f.: 2*x*(3 - 3*x - 48*x^2 + 36*x^3 + 273*x^4 - 173*x^5 - 602*x^6 + 305*x^7 + 502*x^8 - 216*x^9 - 120*x^10 + 48*x^11) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 - 3*x + x^2)*(1 + x - x^2)*(1 - x - x^2)*(1 - 2*x - 4*x^2)). - Colin Barker, Mar 06 2018

Example

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

Crossrefs

Cf. A207752.

Sequence in context: A086113 A207903 A267714 * A208023 A207961 A207243

Adjacent sequences: A207744 A207745 A207746 * A207748 A207749 A207750

Keyword

nonn

Author

R. H. Hardin, Feb 19 2012

Status

approved