A234914 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 2, with no adjacent elements equal (constant-stress tilted 1 X 1 tilings).

40, 120, 376, 1200, 3848, 12360, 39720, 127664, 410344, 1318968, 4239576, 13627344, 43802632, 140795656, 452562248, 1454679760, 4675805864, 15029535096, 48309731384, 155282923376, 499128966408, 1604360091208, 5156926316648

Offset

1,1

Links

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

Formula

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

Empirical g.f.: 8*x*(5 - 5*x - 3*x^2 + 2*x^3) / ((1 - x)*(1 - 3*x - x^2 + x^3)). - Colin Barker, Oct 16 2018

Example

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

Crossrefs

Column 1 of A234921.

Sequence in context: A199807 A199810 A185762 * A043470 A044291 A044672

Adjacent sequences: A234911 A234912 A234913 * A234915 A234916 A234917

Keyword

nonn

Author

R. H. Hardin, Jan 01 2014

Status

approved