A183774 Half the number of (n+1)X2 binary arrays with no 2X2 subblock having exactly 2 ones

5, 13, 33, 85, 217, 557, 1425, 3653, 9353, 23965, 61377, 157237, 402745, 1031693, 2642673, 6769445, 17340137, 44417917, 113778465, 291450133, 746563993, 1912364525, 4898620497, 12548078597, 32142560585, 82334874973, 210905117313

Offset

1,1

Comments

Column 1 of A183782.

a(n) appears to be sum of the elements of the n-th power of the matrix {{1, 2}, {2, 0}}. - Griffin N. Macris, Mar 25 2016

Links

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

Formula

Empirical: a(n) = a(n-1) + 4*a(n-2).

Example

Some solutions with a(1,1)=0 for 3X2
..0..1....0..0....0..1....0..1....0..1....0..0....0..0....0..1....0..0....0..0
..1..1....0..1....1..1....0..0....0..0....0..1....1..0....1..1....0..0....1..0
..1..1....0..0....1..0....1..0....0..0....1..1....1..1....0..1....0..0....0..0

Crossrefs

Sequence in context: A100227 A185454 A278764 * A027051 A109786 A283959

Adjacent sequences: A183771 A183772 A183773 * A183775 A183776 A183777

Keyword

nonn

Author

R. H. Hardin, Jan 07 2011

Status

approved