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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; internal format)
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OFFSET
| 0,2
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COMMENTS
| A133647 is a companion sequence.
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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 (mathar(AT)strw.leidenuniv.nl), Oct 30 2008]
a(n) = A038754(n)^2. - T. D. Noe, Jun 10 2011
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EXAMPLE
| a(4) = 3^4 = 81.
a(5) = 324 = 4 * 3^4.
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MATHEMATICA
| Table[3^(n - 2) ((-1)^n + 7)/2, {n, 1, 60}] (* From Vladimir Joseph Stephan Orlovsky, Jun 10 2011 *)
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CROSSREFS
| Cf. A000244, A133647.
Sequence in context: A118547 A115700 A029806 * A126161 A179934 A018224
Adjacent sequences: A133122 A133123 A133124 * A133126 A133127 A133128
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KEYWORD
| nonn
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AUTHOR
| Gary W. Adamson (qntmpkt(AT)yahoo.com), Sep 19 2007
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