A234221 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 3 (constant-stress 1 X 1 tilings).

436, 1560, 5612, 20724, 76972, 293316, 1123724, 4410276, 17381356, 70026180, 282816332, 1165000164, 4801317292, 20141219076, 84366071564, 359107872036, 1523522391916, 6560162278980, 28109589007052, 122141175701604

Offset

1,1

Links

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

Formula

Empirical: a(n) = 7*a(n-1) + 20*a(n-2) - 224*a(n-3) + 144*a(n-4) + 1680*a(n-5) - 2880*a(n-6).

Empirical g.f.: 4*x*(109 - 373*x - 3507*x^2 + 11976*x^3 + 26580*x^4 - 90000*x^5) / ((1 - 3*x)*(1 - 4*x)*(1 - 12*x^2)*(1 - 20*x^2)). - Colin Barker, Oct 14 2018

Example

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

Crossrefs

Column 2 of A234227.

Sequence in context: A260366 A250781 A260012 * A255777 A283928 A278176

Adjacent sequences: A234218 A234219 A234220 * A234222 A234223 A234224

Keyword

nonn

Author

R. H. Hardin, Dec 21 2013

Status

approved