A234876 Number of (n+1) X (2+1) 0..4 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 1, with no adjacent elements equal (constant-stress tilted 1 X 1 tilings).

68, 148, 268, 628, 1188, 2944, 5684, 14604, 28492, 74816, 146772, 390308, 767956, 2057064, 4053820, 10903852, 21506484, 57986664, 114425348, 308952828, 609818236, 1647911016, 3253169924, 8795476020, 17364799332, 46963065504

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 10*a(n-2) - 21*a(n-3) - 29*a(n-4) + 68*a(n-5) + 22*a(n-6) - 73*a(n-7) + 22*a(n-9).

Empirical g.f.: 4*x*(17 + 3*x - 177*x^2 + 10*x^3 + 583*x^4 - 104*x^5 - 671*x^6 + 110*x^7 + 231*x^8) / ((1 - x)*(1 - x - x^2)*(1 - 10*x^2 + 29*x^4 - 22*x^6)). - Colin Barker, Oct 16 2018

Example

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

Crossrefs

Column 2 of A234882.

Sequence in context: A044191 A044572 A153677 * A044319 A044700 A063341

Adjacent sequences: A234873 A234874 A234875 * A234877 A234878 A234879

Keyword

nonn

Author

R. H. Hardin, Jan 01 2014

Status

approved