A234261 Number of (n+1) X (3+1) 0..2 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 2 (constant-stress 1 X 1 tilings).

104, 170, 292, 560, 1100, 2324, 4924, 10988, 24284, 56060, 127132, 300380, 693020, 1664924, 3887644, 9452828, 22260764, 54595100, 129337372, 319132700, 759181340, 1881143324, 4487847964, 11152445468, 26658390044, 66377408540, 158876074012

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 6*a(n-2) - 24*a(n-3) + 4*a(n-4) + 36*a(n-5) - 24*a(n-6).

Empirical g.f.: 2*x*(52 - 71*x - 421*x^2 + 580*x^3 + 666*x^4 - 876*x^5) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)*(1 - 6*x^2)). - Colin Barker, Oct 14 2018

Example

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

Crossrefs

Column 3 of A234266.

Sequence in context: A253693 A168528 A259767 * A260288 A044336 A044717

Adjacent sequences: A234258 A234259 A234260 * A234262 A234263 A234264

Keyword

nonn

Author

R. H. Hardin, Dec 22 2013

Status

approved