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Search: id:A133125
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OFFSET
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0,2
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COMMENT
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A133647 is a companion sequence.
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FORMULA
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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]
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EXAMPLE
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a(4) = 3^4 = 81.
a(5) = 324 = 4 * 3^4.
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CROSSREFS
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Cf. A000244, A133647.
Sequence in context: A118547 A115700 A029806 this_sequence A126161 A018224 A149137
Adjacent sequences: A133122 A133123 A133124 this_sequence A133126 A133127 A133128
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KEYWORD
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nonn
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AUTHOR
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Gary W. Adamson (qntmpkt(AT)yahoo.com), Sep 19 2007
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