A206190 Number of (n+1) X 2 0..3 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to two.

124, 1012, 8304, 68180, 559788, 4596072, 37735460, 309822148, 2543754976, 20885173732, 171475038268, 1407873792488, 11559167069396, 94905057577684, 779205793959872, 6397569158457620, 52526420432849004, 431261433077432552

Offset

1,1

Comments

Column 1 of A206197.

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 7*a(n-2) + 4*a(n-3) + 2*a(n-4).

Empirical g.f.: 4*x*(31 - 26*x + 16*x^2 + 8*x^3) / (1 - 9*x + 7*x^2 - 4*x^3 - 2*x^4). - Colin Barker, Jun 14 2018

Example

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

Crossrefs

Cf. A206197.

Sequence in context: A206085 A206078 A206197 * A251381 A251374 A209730

Adjacent sequences: A206187 A206188 A206189 * A206191 A206192 A206193

Keyword

nonn

Author

R. H. Hardin, Feb 04 2012

Status

approved