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A117855 Number of palindromes of length n (in base 3). 0
2, 2, 6, 6, 18, 18, 54, 54, 162, 162, 486, 486 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

FORMULA

a(n) = 2*3^floor((n-1)/2)

CROSSREFS

Cf. A050683.

Sequence in context: A140833 A071908 A011260 * A086442 A071407 A109859

Adjacent sequences:  A117852 A117853 A117854 * A117856 A117857 A117858

KEYWORD

nonn,base

AUTHOR

Martin Renner (martin.renner(AT)gmx.net), May 02 2006

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Last modified February 17 03:45 EST 2012. Contains 205978 sequences.