A234721 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 7 (constant-stress 1 X 1 tilings).

240, 1096, 4192, 19120, 74496, 339328, 1344640, 6116416, 24606720, 111778816, 455721472, 2067523840, 8527405056, 38641758208, 160972933120, 728673166336, 3061520302080, 13845560836096, 58597910781952, 264790110146560

Offset

1,1

Links

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

Formula

Empirical: a(n) = 68*a(n-2) - 1724*a(n-4) + 19312*a(n-6) - 80640*a(n-8).

Empirical g.f.: 8*x*(30 + 137*x - 1516*x^2 - 6926*x^3 + 25400*x^4 + 116084*x^5 - 141120*x^6 - 645120*x^7) / ((1 - 4*x)*(1 + 4*x)*(1 - 14*x^2)*(1 - 18*x^2)*(1 - 20*x^2)). - Colin Barker, Oct 16 2018

Example

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

Crossrefs

Column 1 of A234728.

Sequence in context: A124352 A158562 A234728 * A235212 A235205 A233878

Adjacent sequences: A234718 A234719 A234720 * A234722 A234723 A234724

Keyword

nonn

Author

R. H. Hardin, Dec 30 2013

Status

approved