A207501 Number of 4Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 0 0 vertically.

9, 81, 297, 1004, 2942, 7305, 17911, 40262, 87990, 187012, 385400, 783726, 1564402, 3084097, 6019187, 11629307, 22307563, 42493220, 80468378, 151622295, 284370183, 531240776, 988874960, 1834816342, 3394683936, 6264203818, 11531988896

Offset: 1

Author

R. H. Hardin Feb 18 2012

Keywords

• nonn

Comments

Row 4 of A207500

Examples

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

Links

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

Formula

Empirical: a(n) = 4*a(n-1) -a(n-2) -10*a(n-3) -3*a(n-4) +28*a(n-5) +4*a(n-6) -32*a(n-7) -15*a(n-8) +26*a(n-9) +8*a(n-10) -6*a(n-11) +8*a(n-12) -4*a(n-13) -13*a(n-14) -2*a(n-15) +11*a(n-16) -2*a(n-17) +a(n-18) -2*a(n-21) +a(n-22)