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A133125 A133080 * A000244. 1
1, 4, 9, 36, 81, 324, 729, 2916, 6561, 26244, 59049, 236196, 531441, 2125764, 4782969, 19131876, 43046721, 172186884, 387420489, 1549681956, 3486784401, 13947137604, 31381059609, 125524238436, 282429536481, 1129718145924, 2541865828329, 10167463313316 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

A133647 is a companion sequence.

LINKS

Table of n, a(n) for n=0..27.

Index entries for linear recurrences with constant coefficients, signature (0, 9).

FORMULA

A133080 * A000244, where A000244 = (3^0, 3^1, 3^2,...). For even n, a(n) = 3^n. For odd n, a(n) = 4 * 3^(n-1).

G.f.: (1+4x)/((1+3x)(1-3x)). a(n)=9*a(n-2). [From R. J. Mathar, Oct 30 2008]

a(n) = A038754(n)^2. - T. D. Noe, Jun 10 2011

EXAMPLE

a(4) = 3^4 = 81.

a(5) = 324 = 4 * 3^4.

MATHEMATICA

Table[3^(n - 2) ((-1)^n + 7)/2, {n, 1, 60}] (* Vladimir Joseph Stephan Orlovsky, Jun 10 2011 *)

LinearRecurrence[{0, 9}, {1, 4}, 30] (* Harvey P. Dale, Mar 27 2017 *)

CROSSREFS

Cf. A000244, A133647.

Sequence in context: A118547 A115700 A029806 * A126161 A179934 A239213

Adjacent sequences:  A133122 A133123 A133124 * A133126 A133127 A133128

KEYWORD

nonn

AUTHOR

Gary W. Adamson, Sep 19 2007

STATUS

approved

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Last modified August 20 05:25 EDT 2019. Contains 326139 sequences. (Running on oeis4.)