A207881 Number of nX4 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 1 and 1 1 0 vertically.

9, 81, 221, 575, 1673, 4881, 14825, 45411, 141381, 443159, 1399925, 4442717, 14159449, 45263327, 145061281, 465794335, 1498036809, 4823779033, 15548389529, 50156459339, 161898944109, 522854621863, 1689250105197, 5459434154405

Offset: 1

Author

R. H. Hardin Feb 21 2012

Keywords

• nonn

Comments

Column 4 of A207885

Examples

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

Links

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

Formula

Empirical: a(n) = 8*a(n-1) -10*a(n-2) -67*a(n-3) +164*a(n-4) +194*a(n-5) -751*a(n-6) -172*a(n-7) +1630*a(n-8) -197*a(n-9) -1808*a(n-10) +490*a(n-11) +952*a(n-12) -320*a(n-13) -176*a(n-14) +64*a(n-15) for n>16