A207730 Number of 3 X n 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 1 1 and 1 0 1 vertically.

6, 36, 78, 169, 611, 2209, 6016, 16384, 51840, 164025, 478305, 1394761, 4249238, 12945604, 38516590, 114597025, 345332595, 1040643081, 3114412896, 9320743936, 27998628896, 84105220081, 252138754753, 755885919889, 2268515874246

Offset: 1

Author

R. H. Hardin, Feb 19 2012

Keywords

• nonn

Comments

Row 3 of A207729.

Examples

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

Links

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

Crossrefs

Cf. A207729.

Formula

Empirical: a(n) = 2*a(n-1) + 5*a(n-3) + 22*a(n-4) - 24*a(n-5) - 15*a(n-6) - 36*a(n-8) + 27*a(n-9).

Empirical g.f.: x*(6 + 24*x + 6*x^2 - 17*x^3 - 39*x^4 - 51*x^5 - 9*x^6 - 9*x^7 + 27*x^8) / ((1 - 3*x)*(1 + x - x^2)*(1 + x^2)*(1 + 3*x^2 - 9*x^4)). - Colin Barker, Mar 05 2018