A207243 Number of 3Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 0 1 0 vertically.

6, 36, 102, 283, 699, 1526, 3355, 6888, 13954, 27816, 54211, 105147, 201340, 382799, 723838, 1359688, 2544322, 4740623, 8801291, 16292518, 30071783, 55371672, 101727342, 186506700, 341316455, 623552411, 1137394900, 2071676507

Offset: 1

Author

R. H. Hardin Feb 16 2012

Keywords

• nonn

Comments

Row 3 of A207242

Examples

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

Links

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

Formula

Empirical: a(n) = 4*a(n-1) -3*a(n-2) -3*a(n-3) -4*a(n-4) +16*a(n-5) -8*a(n-6) +2*a(n-7) -8*a(n-8) +10*a(n-9) -14*a(n-10) +12*a(n-11) -4*a(n-12) +4*a(n-13) -5*a(n-14) +4*a(n-15) -3*a(n-16) +a(n-17)