A209851 1/4 the number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock having one or four distinct clockwise edge differences.

25, 182, 1308, 9455, 68201, 492373, 3553425, 25648639, 185120173, 1336151135, 9643879893, 69606629219, 502398343961, 3626155026415, 26172443105853, 188904494286595, 1363453261197601, 9840977730403175, 71029086440088981

Offset

1,1

Comments

Column 1 of A209858.

Links

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

Formula

Empirical: a(n) = 4*a(n-1) + 29*a(n-2) - 28*a(n-3) - 110*a(n-4) + 82*a(n-5) - 8*a(n-6).

Empirical g.f.: x*(25 + 82*x - 145*x^2 - 355*x^3 + 295*x^4 - 32*x^5) / (1 - 4*x - 29*x^2 + 28*x^3 + 110*x^4 - 82*x^5 + 8*x^6). - Colin Barker, Jul 13 2018

Example

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

Crossrefs

Cf. A209858.

Sequence in context: A302562 A264259 A209858 * A330126 A243209 A146863

Adjacent sequences: A209848 A209849 A209850 * A209852 A209853 A209854

Keyword

nonn

Author

R. H. Hardin, Mar 14 2012

Status

approved