A206407 Number of (n+1) X 2 0..2 arrays with every 2 X 3 or 3 X 2 subblock having an equal number of clockwise and counterclockwise edge increases.

81, 423, 2457, 15087, 94761, 600519, 3818649, 24314127, 154889673, 986887623, 6288452889, 40071132591, 255342940521, 1627113214023, 10368413881497, 66070427765967, 421019298884361, 2682853284675399, 17095895564336409

Offset

1,1

Comments

Column 1 of A206414.

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 17*a(n-2) + a(n-3) + 4*a(n-4).

Empirical g.f.: 3*x*(27 - 102*x + 9*x^2 + 28*x^3) / ((1 - 2*x - x^2)*(1 - 7*x + 4*x^2)). - Colin Barker, Jun 16 2018

Example

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

Crossrefs

Cf. A206414.

Sequence in context: A205979 A206661 A238173 * A236610 A236704 A236604

Adjacent sequences: A206404 A206405 A206406 * A206408 A206409 A206410

Keyword

nonn

Author

R. H. Hardin, Feb 07 2012

Status

approved