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A116530
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a(n) = 3*a(n-1), with a(1) = 20.
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1
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20, 60, 180, 540, 1620, 4860, 14580, 43740, 131220, 393660, 1180980, 3542940, 10628820, 31886460, 95659380, 286978140, 860934420, 2582803260, 7748409780, 23245229340, 69735688020, 209207064060, 627621192180, 1882863576540
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OFFSET
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1,1
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Tanya Khovanova, Recursive Sequences
Index entries for linear recurrences with constant coefficients, signature (3).
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FORMULA
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a(n) = 10*A008776(n+1).
G.f.: 20*x/(1-3*x). - Philippe Deléham, Nov 23 2008
From G. C. Greubel, Oct 31 2016: (Start)
a(n) = 20*3^(n-1).
E.g.f.: (20/3)*(exp(3*x) - 1). (End)
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MATHEMATICA
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Table[4*5*3^(n - 1), {n, 24}] (* Robert G. Wilson v, May 19 2006 *)
LinearRecurrence[{3}, {20}, 25] (* G. C. Greubel, Oct 31 2016 *)
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PROG
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(MAGMA) [20*3^(n-1): n in [1..30]]; // Vincenzo Librandi, Oct 31 2016
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CROSSREFS
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Sequence in context: A163761 A154072 A078184 * A219830 A041780 A041782
Adjacent sequences: A116527 A116528 A116529 * A116531 A116532 A116533
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KEYWORD
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nonn,less,easy
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AUTHOR
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Ben Gregson (mahishimi(AT)hotmail.com), Mar 26 2006
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STATUS
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approved
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