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A229580 Number of defective 3-colorings of an n X 2 0..2 array connected horizontally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..2 order. 1
1, 6, 40, 224, 1152, 5632, 26624, 122880, 557056, 2490368, 11010048, 48234496, 209715200, 905969664, 3892314112, 16642998272, 70866960384, 300647710720, 1271310319616, 5360119185408, 22539988369408, 94557999988736 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

Empirical: a(n) = 8*a(n-1) - 16*a(n-2) for n>3.

For n > 2: a(n) = 4*a(n-1) + 4^(n-1). - Gerald Hillier, May 01 2018

For n > 1: a(n) = (2n - 1)*2^(2n - 3), [Gerson W. Barbosa]. - Gerald Hillier, May 02 2018

Empirical g.f.: x*(1 - 2*x + 8*x^2) / (1 - 4*x)^2. - Colin Barker, May 02 2018

For n > 1: a(n) = A002064(2n-2) - A002064(2n-3). - Daniel Forgues, Aug 31 2018

EXAMPLE

Some solutions for n=3:

  0 1   0 1   0 1   0 1   0 1   0 1   0 1   0 1   0 1   0 0

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

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

CROSSREFS

Column 2 of A229586.

Sequence in context: A232568 A288637 A059021 * A254945 A026077 A065113

Adjacent sequences:  A229577 A229578 A229579 * A229581 A229582 A229583

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 26 2013

STATUS

approved

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Last modified October 23 12:19 EDT 2019. Contains 328345 sequences. (Running on oeis4.)