A207438 Number of nX4 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 0 1 and 1 0 0 vertically.

9, 81, 323, 1360, 6525, 32393, 165626, 855471, 4449491, 23211486, 121314285, 634633939, 3321850282, 17392770603, 91082814851, 477033173168, 2498544485965, 13087020633451, 68549369291830, 359063591740895, 1880798904630019

Offset: 1

Author

R. H. Hardin Feb 17 2012

Keywords

• nonn

Comments

Column 4 of A207442

Examples

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

Links

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

Formula

Empirical: a(n) = 8*a(n-1) +a(n-2) -120*a(n-3) +106*a(n-4) +730*a(n-5) -804*a(n-6) -2308*a(n-7) +2565*a(n-8) +4000*a(n-9) -4254*a(n-10) -3640*a(n-11) +3811*a(n-12) +1460*a(n-13) -1708*a(n-14) -82*a(n-15) +284*a(n-16) -48*a(n-17) for n>18