A235091 Number of (n+1) X (1+1) 0..5 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 4, with no adjacent elements equal (constant-stress tilted 1 X 1 tilings).

80, 256, 808, 2580, 8184, 26164, 83224, 266572, 849688, 2726852, 8707160, 27993324, 89526552, 288291140, 923287256, 2977443116, 9547498136, 30828553348, 98964094552, 319913934828, 1027967064600, 3326345126596, 10697524464088

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 13*a(n-2) - 39*a(n-3) - 26*a(n-4) + 78*a(n-5).

Empirical g.f.: 4*x*(20 + 4*x - 250*x^2 - 13*x^3 + 501*x^4) / ((1 - 3*x)*(1 - 13*x^2 + 26*x^4)). - Colin Barker, Oct 17 2018

Example

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

Crossrefs

Column 1 of A235098.

Sequence in context: A203355 A203348 A235098 * A306434 A234890 A157912

Adjacent sequences: A235088 A235089 A235090 * A235092 A235093 A235094

Keyword

nonn

Author

R. H. Hardin, Jan 03 2014

Status

approved