A207489 Number of 4Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 1 1 and 1 1 0 vertically.

9, 81, 177, 530, 1322, 2749, 6217, 12712, 25908, 52474, 103704, 205390, 402848, 787367, 1536289, 2987863, 5806685, 11270614, 21859130, 42378217, 82121061, 159101032, 308184196, 596883878, 1155938528, 2238468542, 4334604962

Offset: 1

Author

R. H. Hardin Feb 18 2012

Keywords

• nonn

Comments

Row 4 of A207488

Examples

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

Links

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

Formula

Empirical: a(n) = 2*a(n-1) +2*a(n-2) +a(n-3) -11*a(n-4) -5*a(n-5) +a(n-6) +23*a(n-7) +14*a(n-8) +4*a(n-9) -37*a(n-10) -31*a(n-11) -6*a(n-12) +43*a(n-13) +31*a(n-14) +2*a(n-15) -28*a(n-16) -15*a(n-17) +9*a(n-19) +3*a(n-20) -a(n-22)