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Search: id:A092270
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| A092270 |
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If n mod 2 == 0 then 3^n else 2^n. |
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+0
1
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| 1, 2, 9, 8, 81, 32, 729, 128, 6561, 512, 59049, 2048, 531441, 8192, 4782969, 32768, 43046721, 131072, 387420489, 524288, 3486784401, 2097152, 31381059609, 8388608, 282429536481, 33554432, 2541865828329, 134217728, 22876792454961, 536870912, 205891132094649
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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The convergent series 1/2 + 1/9 + 1/8 + 1/81 + 1/32 + ... fails the ratio test.
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REFERENCES
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B. R. Gelbaum and J. M. H. Olmsted, Counterexamples in Analysis, Holden-Day, San Francisco, 1964; see p. 60.
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FORMULA
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O.g.f.: -(-1+4x^2-2x+18x^3)/((3x-1)(3x+1)(2x-1)(2x+1)) . a(n)=13a(n-2)-36a(n-4) - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 28 2008
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MATHEMATICA
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Table[ If[ EvenQ[n], 3^n, 2^n], {n, 0, 30}] (from Robert G. Wilson v Feb 18 2004)
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CROSSREFS
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Sequence in context: A069815 A162954 A129194 this_sequence A121067 A073904 A036879
Adjacent sequences: A092267 A092268 A092269 this_sequence A092271 A092272 A092273
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Feb 16 2004
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