A206145 Number of (n+1) X 4 0..2 arrays with every 2 X 3 or 3 X 2 subblock having exactly three counterclockwise and three clockwise edge increases.

162, 1122, 7812, 54450, 379602, 2646540, 18451530, 128643282, 896895828, 6253122402, 43596523890, 303953253948, 2119150161594, 14774631788466, 103008153195972, 718168802906322, 5007044718948114, 34908919346114028

Offset

1,1

Comments

Column 3 of A206150.

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 15*a(n-2) + 6*a(n-3).

Empirical g.f.: 6*x*(27 - 56*x + 24*x^2) / (1 - 9*x + 15*x^2 - 6*x^3). - Colin Barker, Jun 13 2018

Example

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

Crossrefs

Cf. A206150.

Sequence in context: A186844 A319915 A302731 * A342850 A304166 A213288

Adjacent sequences: A206142 A206143 A206144 * A206146 A206147 A206148

Keyword

nonn

Author

R. H. Hardin, Feb 04 2012

Status

approved