A207897 Number of 4Xn 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 0 and 1 1 1 vertically.

10, 100, 292, 870, 2446, 6952, 20168, 57838, 164914, 473632, 1360740, 3896086, 11165294, 32038792, 91859552, 263284722, 754983634, 2164966616, 6206791972, 17795617610, 51026354878, 146302277604, 419468202104, 1202710746958

Offset: 1

Author

R. H. Hardin Feb 21 2012

Keywords

• nonn

Comments

Row 4 of A207895

Examples

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

Links

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

Formula

Empirical: a(n) = 3*a(n-2) +10*a(n-3) +18*a(n-4) -2*a(n-5) -22*a(n-6) -7*a(n-7) -12*a(n-9) -8*a(n-10) -6*a(n-11) -6*a(n-12) -3*a(n-13) -a(n-14) +3*a(n-15) +a(n-16) -a(n-17) for n>18