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A206872 Number of 3 X n 0..1 arrays avoiding 0 0 0 horizontally and 1 0 1 vertically. 2
7, 49, 211, 1153, 6139, 31529, 165783, 867545, 4529439, 23698777, 123917699, 647878921, 3387923179, 17715041713, 92629806615, 484357042545, 2532662234303, 13243089222385, 69247131747475, 362087861614577, 1893329530949883 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A206871.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) + 7*a(n-2) + 27*a(n-3) - 13*a(n-4) + a(n-5) - 31*a(n-6) + 5*a(n-7) - 2*a(n-8) + 4*a(n-9).

Empirical g.f.: x*(7 + 28*x + 15*x^2 - 12*x^3 - 29*x^4 - 26*x^5 + 3*x^6 + 2*x^7 + 4*x^8) / ((1 - x)*(1 - 2*x - 9*x^2 - 36*x^3 - 23*x^4 - 24*x^5 + 7*x^6 + 2*x^7 + 4*x^8)). - Colin Barker, Mar 04 2018

EXAMPLE

Some solutions for n=4:

..1..1..1..1....0..1..0..0....1..0..0..1....0..0..1..0....0..0..1..0

..1..1..1..1....1..1..0..0....0..1..0..0....1..0..1..0....0..0..1..1

..1..1..1..1....0..1..1..0....0..0..1..0....0..1..0..0....1..0..0..1

CROSSREFS

Cf. A206871.

Sequence in context: A188608 A188601 A206866 * A133047 A223639 A188689

Adjacent sequences:  A206869 A206870 A206871 * A206873 A206874 A206875

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 13 2012

STATUS

approved

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Last modified January 24 18:53 EST 2022. Contains 350565 sequences. (Running on oeis4.)