A235283 Number of (n+1) X (2+1) 0..3 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 4 (constant-stress 1 X 1 tilings).

40, 68, 104, 188, 304, 572, 968, 1868, 3280, 6428, 11624, 22988, 42544, 84572, 159368, 317708, 607120, 1212188, 2341544, 4678988, 9113584, 18218972, 35712968, 71409548, 140660560, 281288348, 556133864, 1112202188, 2205141424, 4410151772

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 3*a(n-2) - 15*a(n-3) + 4*a(n-4) + 18*a(n-5) - 12*a(n-6).

Empirical g.f.: 4*x*(10 - 13*x - 55*x^2 + 68*x^3 + 72*x^4 - 84*x^5) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)*(1 - 3*x^2)). - Colin Barker, Oct 18 2018

Example

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

Crossrefs

Column 2 of A235289.

Sequence in context: A232870 A338373 A355778 * A134216 A043156 A039333

Adjacent sequences: A235280 A235281 A235282 * A235284 A235285 A235286

Keyword

nonn

Author

R. H. Hardin, Jan 05 2014

Status

approved