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A183774 Half the number of (n+1)X2 binary arrays with no 2X2 subblock having exactly 2 ones 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified October 21 12:49 EDT 2018. Contains 316421 sequences. (Running on oeis4.)