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A083423 a(n) = (5*3^n + (-3)^n)/6. 1
1, 2, 9, 18, 81, 162, 729, 1458, 6561, 13122, 59049, 118098, 531441, 1062882, 4782969, 9565938, 43046721, 86093442, 387420489, 774840978, 3486784401, 6973568802, 31381059609, 62762119218, 282429536481, 564859072962 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..25.

Index entries for linear recurrences with constant coefficients, signature (0,9)

FORMULA

From Reinhard Zumkeller, Mar 04 2011: (Start)

G.f.: (1+2x)/((1-3x)*(1+3x)).

E.g.f.: (5*exp(3x) + exp(-3x))/6.

a(n+3) = a(n+2)*a(n+1)/a(n). (End)

a(n) = 9*a(n-2). - Vincenzo Librandi, Mar 20 2011

MATHEMATICA

LinearRecurrence[{0, 9}, {1, 2}, 30] (* Harvey P. Dale, Dec 04 2019 *)

CROSSREFS

Cf. A083424.

Sequence in context: A280588 A191520 A037421 * A068978 A006226 A109298

Adjacent sequences:  A083420 A083421 A083422 * A083424 A083425 A083426

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Apr 30 2003

STATUS

approved

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Last modified June 23 11:29 EDT 2021. Contains 345397 sequences. (Running on oeis4.)