A207484 Number of nX4 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 1 1 and 1 1 0 vertically.

9, 81, 217, 530, 1459, 3947, 11306, 32445, 96201, 286920, 873201, 2673027, 8288284, 25824249, 81128201, 255825008, 811028901, 2578371055, 8225731808, 26296176189, 84258830581, 270382678904, 868986130961, 2795785995547, 9004226853968

Offset: 1

Author

R. H. Hardin Feb 18 2012

Keywords

• nonn

Comments

Column 4 of A207488

Examples

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

Links

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

Formula

Empirical: a(n) = 8*a(n-1) -5*a(n-2) -106*a(n-3) +209*a(n-4) +518*a(n-5) -1487*a(n-6) -1150*a(n-7) +4949*a(n-8) +938*a(n-9) -8999*a(n-10) +706*a(n-11) +9184*a(n-12) -2042*a(n-13) -5056*a(n-14) +1552*a(n-15) +1334*a(n-16) -472*a(n-17) -128*a(n-18) +48*a(n-19) for n>20