A245866 Number of length n+2 0..5 arrays with some pair in every consecutive three terms totalling exactly 5.

90, 318, 960, 3102, 9726, 30900, 97602, 309078, 977664, 3094038, 9789654, 30977796, 98020170, 310161870, 981426624, 3105480558, 9826505742, 31093507092, 98387556594, 311322635814, 985101990912, 3117106968486, 9863299264806

Offset

1,1

Links

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

Formula

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

Empirical g.f.: 6*x*(15 + 23*x - 6*x^2) / (1 - 2*x - 4*x^2 + x^3). - Colin Barker, Nov 04 2018

Example

Some solutions for n=7:
  1   5   0   3   5   3   2   3   0   4   3   4   1   0   1   3
  5   4   3   1   2   0   2   4   1   0   2   1   4   2   0   0
  0   1   2   4   3   2   3   1   4   5   0   5   2   3   5   5
  2   0   3   5   3   5   4   5   0   0   3   0   1   1   0   0
  3   4   2   0   2   0   1   0   1   5   2   4   3   2   1   2
  2   5   3   5   1   5   4   0   4   3   4   1   2   3   4   5
  0   0   4   0   4   4   4   5   1   2   1   4   4   0   3   0
  5   4   1   3   1   0   1   2   0   0   4   1   3   5   1   4
  2   5   2   2   3   1   5   3   4   3   5   3   1   5   2   1

Crossrefs

Column 5 of A245869.

Sequence in context: A250878 A027621 A331259 * A157888 A201103 A234991

Adjacent sequences: A245863 A245864 A245865 * A245867 A245868 A245869

Keyword

nonn

Author

R. H. Hardin, Aug 04 2014

Status

approved