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 A083581 a(n) = 8/3 - 5*(-2)^n/3. 6
 1, 6, -4, 16, -24, 56, -104, 216, -424, 856, -1704, 3416, -6824, 13656, -27304, 54616, -109224, 218456, -436904, 873816, -1747624, 3495256, -6990504, 13981016, -27962024, 55924056, -111848104, 223696216, -447392424, 894784856, -1789569704, 3579139416, -7158278824 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (-1,2). FORMULA a(n) = (8-5(-2)^n)/3. G.f.: (1+7x)/((1-x)(1+2x)). E.g.f.: (8*exp(x)-5*exp(-2*x))/3. MATHEMATICA Table[(8 - 5 (-2)^n)/3, {n, 0, 40}] (* or *) CoefficientList[Series[(1 + 7 x)/((1 - x) (1 + 2 x)), {x, 0, 40}], x] (* Vincenzo Librandi, Aug 23 2014 *) PROG (Magma) [(8-5*(-2)^n)/3: n in [0..40]]; // Vincenzo Librandi, Aug 23 2014 (PARI) a(n)=8/3-5*(-2)^n/3 \\ Charles R Greathouse IV, Oct 07 2015 CROSSREFS Cf. A083582. Sequence in context: A325689 A199890 A198459 * A171089 A368257 A180495 Adjacent sequences: A083578 A083579 A083580 * A083582 A083583 A083584 KEYWORD easy,sign AUTHOR Paul Barry, May 01 2003 STATUS approved

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Last modified September 13 20:16 EDT 2024. Contains 375910 sequences. (Running on oeis4.)