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A206407 Number of (n+1) X 2 0..2 arrays with every 2 X 3 or 3 X 2 subblock having an equal number of clockwise and counterclockwise edge increases. 1
81, 423, 2457, 15087, 94761, 600519, 3818649, 24314127, 154889673, 986887623, 6288452889, 40071132591, 255342940521, 1627113214023, 10368413881497, 66070427765967, 421019298884361, 2682853284675399, 17095895564336409 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A206414.

LINKS

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

FORMULA

Empirical: a(n) = 9*a(n-1) - 17*a(n-2) + a(n-3) + 4*a(n-4).

Empirical g.f.: 3*x*(27 - 102*x + 9*x^2 + 28*x^3) / ((1 - 2*x - x^2)*(1 - 7*x + 4*x^2)). - Colin Barker, Jun 16 2018

EXAMPLE

Some solutions for n=4:

  1 2   1 2   1 2   0 1   2 0   1 2   1 2   2 1   2 2   1 2

  0 0   1 1   0 1   2 0   2 2   1 2   0 2   0 2   0 0   0 1

  1 2   1 1   2 0   2 2   2 0   1 2   0 1   1 0   2 2   2 0

  0 2   1 0   2 0   0 2   2 2   1 1   0 2   2 1   0 2   2 2

  0 1   1 0   0 1   2 0   0 2   2 1   1 2   1 0   2 0   0 0

CROSSREFS

Cf. A206414.

Sequence in context: A205979 A206661 A238173 * A236610 A236704 A236604

Adjacent sequences:  A206404 A206405 A206406 * A206408 A206409 A206410

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 07 2012

STATUS

approved

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Last modified December 6 18:16 EST 2021. Contains 349567 sequences. (Running on oeis4.)