A209547 1/4 the number of (n+1)X3 0..3 arrays with every 2X2 subblock having exactly two distinct clockwise edge differences

20, 105, 562, 3051, 16582, 90186, 490547, 2668340, 14514612, 78953457, 429474356, 2336164666, 12707780399, 69125130364, 376012453568, 2045354053809, 11125890031368, 60520294171670, 329205663240431, 1790744248612872

Offset

1,1

Comments

Column 2 of A209553

Links

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

Formula

Empirical: a(n) = 8*a(n-1) -14*a(n-2) -3*a(n-3) +20*a(n-4) -8*a(n-5) -2*a(n-6)

Example

Some solutions for n=4
..1..0..1....2..3..2....0..2..0....1..2..3....0..1..2....1..0..1....2..3..0
..0..1..0....3..2..3....2..0..2....0..1..2....1..2..3....2..3..2....1..0..3
..1..2..3....2..1..0....0..2..0....3..2..3....0..3..2....3..2..3....0..1..2
..0..1..0....1..0..1....2..0..2....0..1..2....3..0..1....2..3..2....3..2..1
..1..0..1....2..3..2....0..2..0....1..2..1....0..3..2....1..0..1....2..3..2

Crossrefs

Sequence in context: A334419 A187756 A248087 * A278642 A135174 A173963

Adjacent sequences: A209544 A209545 A209546 * A209548 A209549 A209550

Keyword

nonn

Author

R. H. Hardin Mar 10 2012

Status

approved