A206130 Number of (n+1) X 2 0..3 arrays with every 2 X 3 or 3 X 2 subblock having exactly three counterclockwise and three clockwise edge increases.

256, 564, 3092, 19660, 125236, 797996, 5085012, 32403084, 206481524, 1315758316, 8384382100, 53427641420, 340455961524, 2169481164972, 13824544308692, 88093885500940, 561359021271796, 3577137606898796, 22794527163204372

Offset

1,1

Comments

Column 1 of A206137.

Links

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

Formula

Empirical: a(n) = 8*a(n-1) - 11*a(n-2) + 4*a(n-3) for n > 5.

Empirical g.f.: 4*x*(64 - 371*x + 349*x^2 + 26*x^3 - 72*x^4) / ((1 - x)*(1 - 7*x + 4*x^2)). - Colin Barker, Jun 13 2018

Example

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

Crossrefs

Cf. A206137.

Sequence in context: A235060 A260243 A206137 * A110297 A134608 A134609

Adjacent sequences: A206127 A206128 A206129 * A206131 A206132 A206133

Keyword

nonn

Author

R. H. Hardin, Feb 04 2012

Status

approved