A185790 Number of (n+1) X 2 binary arrays with no 2 X 2 subblock sum equal to any horizontal or vertical neighbor 2 X 2 subblock sum.

16, 40, 100, 260, 676, 1716, 4356, 11220, 28900, 73780, 188356, 483476, 1240996, 3174900, 8122500, 20822100, 53377636, 136666036, 349914436, 896578580, 2297284900, 5883599220, 15068544516, 38602941396, 98893896676, 253305662260

Offset

1,1

Comments

Column 1 of A185798.

Links

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

Formula

Empirical: a(n) = a(n-1) + 4*a(n-3) + 16*a(n-4).

Empirical g.f.: 4*x*(4 + 6*x + 15*x^2 + 24*x^3) / ((1 + 4*x^2)*(1 - x - 4*x^2)). - Colin Barker, Apr 16 2018

Example

Some solutions for 3 X 2:
..1..0....1..0....1..1....0..0....0..1....0..0....1..1....0..0....1..0....1..1
..0..1....0..0....1..0....0..0....0..0....1..0....0..0....1..1....1..0....1..1
..1..1....1..1....0..0....0..1....0..0....1..0....0..1....1..0....0..0....1..0

Crossrefs

Cf. A185798.

Sequence in context: A182461 A205065 A368078 * A185761 A205248 A205186

Adjacent sequences: A185787 A185788 A185789 * A185791 A185792 A185793

Keyword

nonn

Author

R. H. Hardin, Feb 04 2011

Status

approved