A250907 Number of (n+1) X (2+1) 0..2 arrays with no 2 X 2 subblock having its maximum diagonal element less than its minimum antidiagonal element.

603, 13401, 297873, 6621219, 147178899, 3271547025, 72721157625, 1616472795339, 35931555318411, 798699904707465, 17753796965556513, 394637967071813043, 8772158730705164739, 194990789577739653441, 4334327408721425197833

Offset

1,1

Links

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

Formula

Empirical: a(n) = 24*a(n-1) - 41*a(n-2) + 36*a(n-3).

Empirical g.f.: 9*x*(67 - 119*x + 108*x^2) / (1 - 24*x + 41*x^2 - 36*x^3). - Colin Barker, Nov 23 2018

Example

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

Crossrefs

Column 2 of A250913.

Sequence in context: A178032 A107256 A177685 * A209550 A151626 A031792

Adjacent sequences: A250904 A250905 A250906 * A250908 A250909 A250910

Keyword

nonn

Author

R. H. Hardin, Nov 28 2014

Status

approved