A210293 Half the number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock having at most one duplicate clockwise edge difference.

112, 1578, 22212, 312704, 4402192, 61973516, 872455004, 12282307884, 172908727756, 2434186513236, 34268160178956, 482422688537636, 6791483674595260, 95609621185469444, 1345979774260696316

Offset

1,1

Comments

Column 1 of A210300.

Links

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

Formula

Empirical: a(n) = 11*a(n-1) + 42*a(n-2) + 20*a(n-3) - 18*a(n-4).

Empirical g.f.: 2*x*(56 + 173*x + 75*x^2 - 72*x^3) / (1 - 11*x - 42*x^2 - 20*x^3 + 18*x^4). - Colin Barker, Jul 15 2018

Example

Some solutions for n=4:
..2..0....3..1....3..2....1..3....1..1....1..0....2..3....1..0....1..3....2..1
..3..0....1..0....3..0....1..3....2..2....2..0....0..1....0..0....2..2....1..1
..2..0....2..2....1..1....3..2....1..0....1..2....2..0....0..3....0..2....3..3
..3..1....1..1....1..2....1..3....0..3....1..3....0..1....1..3....2..1....0..1
..1..2....0..3....2..2....0..1....0..0....0..0....3..0....1..0....1..1....0..0

Crossrefs

Cf. A210300.

Sequence in context: A367363 A327633 A210300 * A203915 A233884 A246895

Adjacent sequences: A210290 A210291 A210292 * A210294 A210295 A210296

Keyword

nonn

Author

R. H. Hardin, Mar 19 2012

Status

approved