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A229472 Number of defective 4-colorings of an n X 1 0..3 array connected horizontally, antidiagonally and vertically with exactly one mistake, and colors introduced in row-major 0..3 order. 2
0, 1, 2, 6, 20, 70, 246, 854, 2920, 9846, 32810, 108262, 354300, 1151462, 3720094, 11957430, 38263760, 121965718, 387420498, 1226831558, 3874204900, 12203745414, 38354628422, 120294061846, 376572715320, 1176789735350, 3671583974266 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Column 1 of A229479.

LINKS

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

FORMULA

Empirical: a(n) = 8*a(n-1) - 22*a(n-2) + 24*a(n-3) - 9*a(n-4) for n>6.

Conjectures from Colin Barker, Mar 16 2018: (Start)

G.f.: x^2*(1 - 6*x + 12*x^2 - 8*x^3 + 3*x^4) / ((1 - x)^2*(1 - 3*x)^2).

a(n) = (27+3^n) * (n-1) / 54 for n>2.

(End)

EXAMPLE

All solutions for n=4:

  0      0      0      0      0      0

  0      1      1      1      1      0

  1      0      1      2      1      1

  0      0      2      2      0      2

CROSSREFS

Cf. A229479.

Sequence in context: A150124 A045631 A275046 * A135413 A193653 A147748

Adjacent sequences:  A229469 A229470 A229471 * A229473 A229474 A229475

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 24 2013

STATUS

approved

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Last modified June 18 04:41 EDT 2021. Contains 345098 sequences. (Running on oeis4.)