A250951 Number of (n+1) X (3+1) 0..1 arrays with no 2 X 2 subblock having its maximum diagonal element less than its minimum antidiagonal element.

209, 2744, 36016, 472712, 6204344, 81431944, 1068793208, 14027896712, 184115958136, 2416519505288, 31716786410360, 416282400363400, 5463700975560056, 71711002733396360, 941205958384596856

Offset

1,1

Links

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

Formula

Empirical: a(n) = 15*a(n-1) - 24*a(n-2) - 8*a(n-3).

Empirical g.f.: x*(209 - 391*x - 128*x^2) / (1 - 15*x + 24*x^2 + 8*x^3). - Colin Barker, Nov 24 2018

Example

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

Crossrefs

Column 3 of A250956.

Sequence in context: A235731 A235512 A203040 * A304765 A316509 A317463

Adjacent sequences: A250948 A250949 A250950 * A250952 A250953 A250954

Keyword

nonn

Author

R. H. Hardin, Nov 28 2014

Status

approved