A207112 Number of 3Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 1 0 vertically.

6, 36, 98, 271, 677, 1504, 3399, 7220, 15184, 31664, 64749, 132543, 268994, 544151, 1099824, 2215226, 4461522, 8974915, 18040615, 36261642, 72844037, 146324852, 293885650, 590165228, 1185140667, 2379732659, 4778367860, 9594547523

Offset: 1

Author

R. H. Hardin Feb 15 2012

Keywords

• nonn

Comments

Row 3 of A207111

Examples

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

Links

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

Formula

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