A235080 Number of (n+1) X (1+1) 0..4 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).

38, 90, 202, 478, 1078, 2554, 5786, 13726, 31238, 74202, 169642, 403486, 926614, 2206714, 5090042, 12136798, 28113638, 67114074, 156091786, 373047646, 870937078, 2083671802, 4882030682, 11691483166, 27483747014, 65877727194

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 6*a(n-2) - 10*a(n-3) - 5*a(n-4).

Empirical g.f.: 2*x*(19 + 7*x - 103*x^2 - 43*x^3) / ((1 - 2*x - x^2)*(1 - 5*x^2)). - Colin Barker, Oct 17 2018

Example

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

Crossrefs

Column 1 of A235087.

Sequence in context: A014716 A137028 A235087 * A218331 A124141 A093649

Adjacent sequences: A235077 A235078 A235079 * A235081 A235082 A235083

Keyword

nonn

Author

R. H. Hardin, Jan 03 2014

Status

approved