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A209220 Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 1 0 and 1 1 1 vertically. 1
9, 81, 100, 196, 324, 576, 1024, 1764, 3136, 5476, 9604, 16900, 29584, 51984, 91204, 160000, 280900, 492804, 864900, 1517824, 2663424, 4674244, 8202496, 14394436, 25260676, 44328964, 77792400, 136515856, 239568484, 420414016, 737774244 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A209224.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + a(n-2) + a(n-3) - a(n-4) + a(n-5) - a(n-6) for n > 8.

Empirical g.f.: x*(9 + 72*x + 10*x^2 + 6*x^3 - 44*x^4 + 28*x^5 - 44*x^6 + 17*x^7) / ((1 - 2*x + x^2 - x^3)*(1 + x - x^3)). - Colin Barker, Jul 08 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A209224.

Sequence in context: A043087 A037414 A161147 * A207689 A209225 A208502

Adjacent sequences:  A209217 A209218 A209219 * A209221 A209222 A209223

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 06 2012

STATUS

approved

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Last modified October 17 22:21 EDT 2019. Contains 328134 sequences. (Running on oeis4.)