A207712 Number of n X 3 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 0 0 vertically.

6, 36, 114, 387, 1414, 5302, 20265, 78120, 302850, 1177545, 4587102, 17888094, 69803695, 272499292, 1064042682, 4155446955, 16229927982, 63392825886, 247616093433, 967223892240, 3778165401850, 14758373590129, 57649858583478

Offset

1,1

Comments

Column 3 of A207717.

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 4*a(n-2) - 23*a(n-3) + 20*a(n-4) + 28*a(n-5) - 13*a(n-6) - 14*a(n-7) + a(n-9) for n>10.

Empirical g.f.: x*(6 - 78*x^2 - 15*x^3 + 256*x^4 + 100*x^5 - 200*x^6 - 120*x^7 + 6*x^8 + 9*x^9) / ((1 - x)*(1 - x - x^2)*(1 - 2*x - x^2)*(1 - 2*x - 7*x^2 - 2*x^3 + x^4)). - Colin Barker, Mar 05 2018

Example

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

Crossrefs

Cf. A207717.

Sequence in context: A061804 A207421 A207427 * A207718 A262467 A225262

Adjacent sequences: A207709 A207710 A207711 * A207713 A207714 A207715

Keyword

nonn

Author

R. H. Hardin, Feb 19 2012

Status

approved