A206004 Number of (n+1) X 3 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to one, and every 2 X 2 determinant nonzero.

78, 300, 980, 3706, 12304, 45810, 154346, 567112, 1932816, 7031026, 24170780, 87268194, 301959592, 1084079204, 3769438358, 13475470000, 47028047126, 167585570856, 586477834058, 2084911242168, 7311507381518, 25945246790130

Offset

1,1

Comments

Column 2 of A206010.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 13*a(n-2) - 17*a(n-3) - 34*a(n-4) - 9*a(n-5) + 23*a(n-6) + a(n-7) - 4*a(n-8) + a(n-9).

Empirical g.f.: 2*x*(39 + 72*x - 317*x^2 - 414*x^3 - 48*x^4 + 293*x^5 + x^6 - 48*x^7 + 13*x^8) / (1 - 2*x - 13*x^2 + 17*x^3 + 34*x^4 + 9*x^5 - 23*x^6 - x^7 + 4*x^8 - x^9). - Colin Barker, Jun 13 2018

Example

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

Crossrefs

Cf. A206010.

Sequence in context: A068130 A118938 A362546 * A317412 A231393 A231461

Adjacent sequences: A206001 A206002 A206003 * A206005 A206006 A206007

Keyword

nonn

Author

R. H. Hardin, Feb 02 2012

Status

approved