A250967 Number of (n+1) X (2+1) 0..1 arrays with no 2 X 2 subblock having the sum of its diagonal elements less than the absolute difference of its antidiagonal elements.

49, 308, 1945, 12281, 77537, 489543, 3090834, 19514643, 123209858, 777911692, 4911511266, 31009873218, 195787443967, 1236145757310, 7804669708967, 49276445682891, 311117342524943, 1964305653103961, 12402062409962968

Offset

1,1

Links

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

Formula

Empirical: a(n) = 8*a(n-1) - 13*a(n-2) + 17*a(n-3) - 14*a(n-4) + 3*a(n-5).

Empirical g.f.: x*(49 - 84*x + 118*x^2 - 108*x^3 + 24*x^4) / ((1 - x)*(1 - 7*x + 6*x^2 - 11*x^3 + 3*x^4)). - Colin Barker, Nov 24 2018

Example

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

Crossrefs

Column 2 of A250973.

Sequence in context: A239607 A227079 A251222 * A245033 A340124 A017474

Adjacent sequences: A250964 A250965 A250966 * A250968 A250969 A250970

Keyword

nonn

Author

R. H. Hardin, Nov 29 2014

Status

approved