A234260 Number of (n+1) X (2+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).

46, 88, 170, 358, 754, 1690, 3746, 8722, 19906, 47458, 110210, 266818, 626434, 1532290, 3623426, 8925442, 21208066, 52491778, 125134850, 310731778, 742387714, 1847564290, 4420706306, 11018178562, 26389889026, 65840439298, 157802201090

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*(23 - 25*x - 185*x^2 + 212*x^3 + 294*x^4 - 324*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:
  2 2 2   2 0 2   2 1 2   1 1 1   2 2 2   2 1 2   1 1 1
  2 0 2   0 0 0   1 2 1   0 2 0   0 2 0   0 1 0   0 2 0
  1 1 1   2 0 2   1 0 1   1 1 1   1 1 1   1 0 1   0 0 0
  0 2 0   1 1 1   1 2 1   2 0 2   2 0 2   0 1 0   0 2 0
  1 1 1   0 2 0   1 0 1   1 1 1   1 1 1   1 0 1   0 0 0
  0 2 0   1 1 1   0 1 0   0 2 0   2 0 2   0 1 0   2 0 2

Crossrefs

Column 2 of A234266.

Sequence in context: A363049 A057454 A260278 * A211330 A121929 A007630

Adjacent sequences: A234257 A234258 A234259 * A234261 A234262 A234263

Keyword

nonn

Author

R. H. Hardin, Dec 22 2013

Status

approved