A206131 Number of (n+1) X 3 0..3 arrays with every 2 X 3 or 3 X 2 subblock having exactly three counterclockwise and three clockwise edge increases.

564, 6668, 91924, 1269044, 17521788, 241927532, 3340355572, 46121153588, 636806710044, 8792555155244, 121401086008468, 1676216233423412, 23143951620064572, 319554533544992108, 4412172198832106164

Offset

1,1

Comments

Column 2 of A206137.

Links

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

Formula

Empirical: a(n) = 17*a(n-1) - 47*a(n-2) + 41*a(n-3) - 10*a(n-4) for n > 5.

Empirical g.f.: 4*x*(3 - 5*x)*(47 - 165*x + 148*x^2 - 36*x^3) / ((1 - x)*(1 - 16*x + 31*x^2 - 10*x^3)). - Colin Barker, Jun 13 2018

Example

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

Crossrefs

Cf. A206137.

Sequence in context: A252293 A252286 A252285 * A283782 A203781 A189352

Adjacent sequences: A206128 A206129 A206130 * A206132 A206133 A206134

Keyword

nonn

Author

R. H. Hardin, Feb 04 2012

Status

approved