A207886 Number of 4Xn 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 1 and 1 1 0 vertically.

9, 81, 177, 575, 1360, 3106, 8652, 22114, 53620, 139806, 360132, 899952, 2300016, 5898082, 14925674, 37975776, 96993892, 246541258, 627068300, 1598281686, 4067781864, 10349972204, 26357799164, 67101532924, 170780094962

Offset: 1

Author

R. H. Hardin Feb 21 2012

Keywords

• nonn

Comments

Row 4 of A207885

Examples

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

Links

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

Formula

Empirical: a(n) = a(n-1) +a(n-2) +11*a(n-3) -2*a(n-4) -7*a(n-5) -31*a(n-6) +a(n-7) +6*a(n-8) +39*a(n-9) -4*a(n-10) +7*a(n-11) -24*a(n-12) -a(n-13) -6*a(n-14) +6*a(n-15) for n>17