A207961 Number of 3 X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 1 0 0 vertically.

6, 36, 102, 281, 699, 1799, 4706, 12161, 31356, 81206, 210185, 543399, 1405547, 3636320, 9405751, 24328772, 62932300, 162787659, 421078225, 1089199555, 2817430618, 7287821163, 18851338264, 48762622760, 126133900375, 326269518673

Offset

1,1

Comments

Row 3 of A207960.

Links

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

Formula

Empirical: a(n) = a(n-1) + a(n-2) + 7*a(n-3) + 4*a(n-4) - 7*a(n-6) - 6*a(n-7) + 6*a(n-9) + 2*a(n-10) - a(n-11) - a(n-12) for n>13.

Empirical g.f.: x*(6 + 30*x + 60*x^2 + 101*x^3 + 40*x^4 - 39*x^5 - 125*x^6 - 73*x^7 + 30*x^8 + 94*x^9 + 23*x^10 - 19*x^11 - 15*x^12) / ((1 + x^2 - x^3)*(1 - x - 2*x^2 - 5*x^3 - 3*x^4 + 3*x^5 + 5*x^6 - 2*x^8 - x^9)). - Colin Barker, Mar 06 2018

Example

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

Crossrefs

Cf. A207960.

Sequence in context: A267714 A207747 A208023 * A207243 A207237 A207070

Adjacent sequences: A207958 A207959 A207960 * A207962 A207963 A207964

Keyword

nonn

Author

R. H. Hardin, Feb 21 2012

Status

approved