A209532 Half the number of (n+1) X 7 0..2 arrays with every 2 X 2 subblock having exactly two distinct clockwise edge differences.

129, 1537, 16385, 196609, 2097153, 25165825, 268435457, 3221225473, 34359738369, 412316860417, 4398046511105, 52776558133249, 562949953421313, 6755399441055745, 72057594037927937, 864691128455135233

Offset

1,1

Comments

Column 6 of A209534.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = a(n-1) + 128*a(n-2) - 128*a(n-3).

Conjectures from Colin Barker, Jul 11 2018: (Start)

G.f.: x*(129 + 1408*x - 1664*x^2) / ((1 - x)*(1 - 128*x^2)).

a(n) = 3*2^((7*n)/2 + 2) + 1 for n even.

a(n) = 2^((7*n)/2 + 7/2) + 1 for n odd.

(End)

Example

Some solutions for n=4:
..0..1..2..1..2..1..2....0..1..2..1..2..1..0....1..2..1..2..1..2..1
..1..2..1..2..1..2..1....1..0..1..0..1..0..1....2..1..0..1..2..1..2
..0..1..0..1..0..1..0....2..1..2..1..0..1..2....1..2..1..0..1..2..1
..1..2..1..2..1..2..1....1..0..1..2..1..0..1....0..1..2..1..2..1..0
..2..1..2..1..0..1..2....0..1..0..1..2..1..0....1..0..1..0..1..2..1

Crossrefs

Cf. A209534.

Sequence in context: A341552 A251095 A329727 * A233305 A268266 A230187

Adjacent sequences: A209529 A209530 A209531 * A209533 A209534 A209535

Keyword

nonn

Author

R. H. Hardin, Mar 10 2012

Status

approved