A208035 Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 0 and 1 0 1 vertically.

9, 81, 289, 961, 3249, 11025, 37249, 126025, 426409, 1442401, 4879681, 16507969, 55845729, 188925025, 639128961, 2162157001, 7314525625, 24744863025, 83711270241, 283193201281, 958035736849, 3241011678961, 10964263980289

Offset

1,1

Comments

Column 4 of A208039.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 3*a(n-2) + 6*a(n-3) - a(n-4) - a(n-6) for n>7.

Empirical g.f.: x*(9 + 63*x + 100*x^2 + 86*x^3 - 17*x^4 - 9*x^5 - 16*x^6) / ((1 + x + x^2 - x^3)*(1 - 3*x - x^2 - x^3)). - Colin Barker, Jun 27 2018

Example

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

Crossrefs

Cf. A208039.

Sequence in context: A207399 A207904 A207748 * A207124 A207854 A207962

Adjacent sequences: A208032 A208033 A208034 * A208036 A208037 A208038

Keyword

nonn

Author

R. H. Hardin, Feb 22 2012

Status

approved