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A229577 Number of defective 4-colorings of an n X 7 0..3 array connected horizontally, vertically, diagonally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..3 order. 1
246, 1312, 1584, 2064, 2852, 4048, 6108, 9992, 17716, 33504, 66188, 134200, 275940, 571280, 1186108, 2464488, 5119124, 10624576, 22028268, 45621656, 94380868, 195044592, 402663068, 830482504, 1711286772, 3523226528, 7247768908 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 6*a(n-1) - 13*a(n-2) + 12*a(n-3) - 4*a(n-4) for n>7.

Empirical g.f.: 2*x*(123 - 82*x - 1545*x^2 + 3332*x^3 - 1850*x^4 + 4*x^5 + 232*x^6) / ((1 - x)^2*(1 - 2*x)^2). - Colin Barker, Sep 19 2018

EXAMPLE

Some solutions for n=3:

..0..1..2..1..2..1..0....0..1..0..2..3..1..0....0..1..2..1..2..1..2

..3..3..0..3..0..3..2....3..2..3..1..0..2..3....0..3..0..3..0..3..0

..2..1..2..1..2..1..0....0..1..0..2..3..2..0....2..1..2..1..2..1..2

CROSSREFS

Column 7 of A229578.

Sequence in context: A231964 A231965 A067916 * A186796 A186788 A074995

Adjacent sequences:  A229574 A229575 A229576 * A229578 A229579 A229580

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 26 2013

STATUS

approved

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Last modified January 21 16:03 EST 2022. Contains 350479 sequences. (Running on oeis4.)