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

1,1

Comments

Row 4 of A207488

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)

Example

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

Crossrefs

Sequence in context: A044260 A208109 A208841 * A207886 A207731 A208690

Adjacent sequences: A207486 A207487 A207488 * A207490 A207491 A207492

Keyword

nonn

Author

R. H. Hardin Feb 18 2012

Status

approved