A207509 Number of n X 3 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 1 1 vertically.

6, 36, 72, 166, 360, 660, 1292, 2400, 4396, 8096, 14580, 26346, 47336, 84502, 150976, 268594, 477130, 846850, 1500112, 2655880, 4697786, 8303004, 14669200, 25901790, 45719422, 80675866, 142317030, 251007562, 442623618, 780396916, 1375769956

Offset: 1

Author

R. H. Hardin, Feb 18 2012

Keywords

• nonn

Comments

Column 3 of A207514.

Examples

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

Links

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

Crossrefs

Cf. A207514.

Formula

Empirical: a(n) = 2*a(n-1) + 2*a(n-3) - 5*a(n-4) + a(n-5) - 4*a(n-6) + 5*a(n-7) - a(n-8) + 2*a(n-9) - a(n-10) for n>11.

Empirical g.f.: 2*x*(3 + 12*x + 5*x^3 - 7*x^4 - 15*x^5 - 6*x^6 - 16*x^7 + 12*x^8 - 6*x^9 + 2*x^10) / ((1 - x)*(1 - x - x^3)*(1 - x^2 - 3*x^3 - x^4 - x^5 + x^6)). - Colin Barker, Mar 05 2018