A207306 Number of 3 X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 1 1 0 vertically.

6, 36, 98, 271, 665, 1675, 4344, 11081, 28136, 71908, 183709, 468421, 1195165, 3050758, 7784759, 19863812, 50690966, 129357269, 330093729, 842344955, 2149538940, 5485269169, 13997500468, 35719380356, 91150094557, 232600215969

Offset: 1

Author

R. H. Hardin, Feb 16 2012

Keywords

• nonn

Comments

Row 3 of A207305.

Examples

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

Links

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

Crossrefs

Cf. A207305.

Formula

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

Empirical g.f.: x*(6 + 30*x + 56*x^2 + 101*x^3 + 56*x^4 + x^5 - 38*x^6 - 26*x^7 - 2*x^8) / (1 - x - x^2 - 6*x^3 - 4*x^4 - x^5 + 2*x^6 + 2*x^7). - Colin Barker, Mar 05 2018