A235241 Number of (n+1) X (1+1) 0..7 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 6, with no adjacent elements equal (constant-stress tilted 1 X 1 tilings).

210, 906, 3746, 16150, 66874, 288510, 1195458, 5161934, 21400266, 92486622, 383623154, 1659369022, 6886195834, 29811968622, 123773981922, 536299705358, 2227615662378, 9660029955390, 40141785286994, 174215753195230

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) + 39*a(n-2) - 152*a(n-3) - 441*a(n-4) + 1612*a(n-5) + 1185*a(n-6) - 3128*a(n-7) - 782*a(n-8).

Empirical g.f.: 2*x*(105 + 33*x - 4034*x^2 - 1124*x^3 + 43251*x^4 + 10791*x^5 - 84602*x^6 - 20036*x^7) / ((1 - 4*x - x^2)*(1 - 17*x^2)*(1 - 21*x^2 + 46*x^4)). - Colin Barker, Oct 17 2018

Example

Some solutions for n=4:
  4 1   0 1   3 7   5 7   4 6   6 2   5 6   4 7   4 2   4 2
  1 4   5 0   6 4   7 3   5 1   1 3   7 2   5 2   3 7   3 7
  3 0   6 7   3 7   4 6   2 4   4 0   5 6   2 5   2 0   7 5
  1 4   7 2   2 0   5 1   6 2   2 4   7 2   4 1   3 7   2 6
  3 0   6 7   1 5   0 2   1 3   4 0   0 1   2 5   4 2   4 2

Crossrefs

Column 1 of A235248.

Sequence in context: A009127 A158559 A235248 * A046302 A217532 A289319

Adjacent sequences: A235238 A235239 A235240 * A235242 A235243 A235244

Keyword

nonn

Author

R. H. Hardin, Jan 05 2014

Status

approved