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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. 1
25, 182, 1308, 9455, 68201, 492373, 3553425, 25648639, 185120173, 1336151135, 9643879893, 69606629219, 502398343961, 3626155026415, 26172443105853, 188904494286595, 1363453261197601, 9840977730403175, 71029086440088981 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 4 19:40 EST 2021. Contains 349526 sequences. (Running on oeis4.)