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A116530 a(n) = 3*a(n-1), with a(1) = 20. 1
20, 60, 180, 540, 1620, 4860, 14580, 43740, 131220, 393660, 1180980, 3542940, 10628820, 31886460, 95659380, 286978140, 860934420, 2582803260, 7748409780, 23245229340, 69735688020, 209207064060, 627621192180, 1882863576540 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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).

FORMULA

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)

MATHEMATICA

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 *)

PROG

(MAGMA) [20*3^(n-1): n in [1..30]]; // Vincenzo Librandi, Oct 31 2016

CROSSREFS

Sequence in context: A163761 A154072 A078184 * A219830 A041780 A041782

Adjacent sequences:  A116527 A116528 A116529 * A116531 A116532 A116533

KEYWORD

nonn,less,easy

AUTHOR

Ben Gregson (mahishimi(AT)hotmail.com), Mar 26 2006

STATUS

approved

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Last modified April 30 22:38 EDT 2017. Contains 285698 sequences.