A209725 1/4 the number of (n+1) X 7 0..2 arrays with every 2 X 2 subblock having distinct clockwise edge differences.

12, 13, 14, 16, 18, 22, 26, 34, 42, 58, 74, 106, 138, 202, 266, 394, 522, 778, 1034, 1546, 2058, 3082, 4106, 6154, 8202, 12298, 16394, 24586, 32778, 49162, 65546, 98314, 131082, 196618, 262154, 393226, 524298, 786442, 1048586, 1572874, 2097162

Offset: 1

Author

R. H. Hardin, Mar 12 2012

Keywords

• nonn

Comments

Column 6 of A209727.

Examples

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

Links

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

Crossrefs

Cf. A209727.

Formula

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

Conjectures from Colin Barker, Jul 12 2018: (Start)

G.f.: x*(12 + x - 23*x^2) / ((1 - x)*(1 - 2*x^2)).

a(n) = 3*2^(n/2 - 1) + 10 for n even.

a(n) = 2^((n + 1)/2) + 10 for n odd.

(End)