A204794 Number of (n+1) X 3 0..1 arrays with rows and columns of determinants of all 2 X 2 subblocks lexicographically nondecreasing.

47, 240, 1001, 4273, 18550, 81009, 353975, 1547377, 6764879, 29576797, 129315563, 565399369, 2472075383, 10808590261, 47258158979, 206625890401, 903426368975, 3950033937229, 17270659001435, 75512178579577, 330160485651239

Offset

1,1

Comments

Column 2 of A204800.

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 5*a(n-2) - 12*a(n-3) + 12*a(n-4) for n > 8.

Empirical g.f.: x*(47 - 42*x - 204*x^2 + 31*x^3 + 233*x^4 + 206*x^5 - 65*x^6 - 104*x^7) / ((1 - x)*(1 - 2*x)*(1 - 3*x - 6*x^2)). - Colin Barker, Jun 10 2018

Example

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

Crossrefs

Cf. A204800.

Sequence in context: A102090 A033226 A142946 * A233823 A142084 A140850

Adjacent sequences: A204791 A204792 A204793 * A204795 A204796 A204797

Keyword

nonn

Author

R. H. Hardin, Jan 19 2012

Status

approved