A183805 1/16 the number of (n+1) X 4 binary arrays with no 2 X 2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor.

9, 55, 322, 1953, 11619, 70044, 418925, 2518389, 15091626, 90619253, 543451183, 3261698460, 19566441353, 117412757177, 704423288546, 4226740369841, 25359685459275, 152160965127516, 912955035168789, 5477770757446957

Offset

1,1

Comments

Column 3 of A183811.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 6*a(n-1) + 12*a(n-2) - 83*a(n-3) + 56*a(n-4) + 60*a(n-5).

Empirical g.f.: x*(9 + x - 116*x^2 + 108*x^3 + 98*x^4) / ((1 - 2*x)*(1 - 6*x)*(1 + 2*x - 8*x^2 - 5*x^3)). - Colin Barker, Apr 04 2018

Example

Some solutions with upper left block zero for 3 X 4:
  0 0 1 1    0 0 0 1    0 0 0 0    0 0 1 1    0 0 0 1
  0 0 0 0    0 0 1 1    0 0 1 1    0 0 1 1    0 0 1 1
  0 1 1 0    1 1 0 0    1 1 1 0    0 1 0 1    1 0 1 0

Crossrefs

Cf. A183811.

Sequence in context: A097790 A356339 A362365 * A037578 A096191 A362088

Adjacent sequences: A183802 A183803 A183804 * A183806 A183807 A183808

Keyword

nonn

Author

R. H. Hardin, Jan 07 2011

Status

approved