A206660 - OEIS

A206660

Number of (n+1) X (n+1) 0..2 arrays with every 2 X 2 subblock having the number of clockwise edge increases equal to the number of counterclockwise edge increases in its adjacent leftward and upward neighbors.

81, 2691, 166605, 25229685, 10351091007, 11143560422013, 30831727837091925, 217363460829124577235, 3903604149526204562445729

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OFFSET

1,1

COMMENTS

Diagonal of A206668.

LINKS

Table of n, a(n) for n=1..9.

EXAMPLE

Some solutions for n=4:

..1..2..0..2..1....2..1..0..2..1....1..2..1..2..1....2..1..2..2..2

..0..0..0..0..0....2..0..1..0..2....1..0..1..0..0....2..2..2..1..1

..1..1..1..2..1....0..2..0..2..1....1..2..1..2..1....1..1..1..1..2

..2..2..0..2..1....1..0..2..1..2....0..0..0..2..0....0..1..2..2..2

..0..1..0..2..1....2..1..0..2..0....1..2..1..2..1....0..1..2..1..2

CROSSREFS

Sequence in context: A210128 A297084 A018223 * A253525 A253741 A253516

Adjacent sequences: A206657 A206658 A206659 * A206661 A206662 A206663

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 11 2012

STATUS

approved