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 A168648 a(n) = (10*2^n + 2*(-1)^n)/3 for n > 0; a(0) = 1. 3
 1, 6, 14, 26, 54, 106, 214, 426, 854, 1706, 3414, 6826, 13654, 27306, 54614, 109226, 218454, 436906, 873814, 1747626, 3495254, 6990506, 13981014, 27962026, 55924054, 111848106, 223696214, 447392426, 894784854, 1789569706, 3579139414 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 Index entries for linear recurrences with constant coefficients, signature (1,2). FORMULA a(n) = A084214(n+2) for n > 0. a(n) = a(n-1) + 2*a(n-2) for n > 2; a(0) = 1, a(1) = 6, a(2) = 14. G.f.: (1+2*x)*(1+3*x)/((1+x)*(1-2*x)). E.g.f.: (1/3)*(10*exp(2*x) - 9 + 2*exp(-x)). - G. C. Greubel, Jul 28 2016 MATHEMATICA {1}~Join~Table[(10*2^n + 2*(-1)^n)/3, {n, 40}] (* or *) {1}~Join~LinearRecurrence[{1, 2}, {6, 14}, 40] (* G. C. Greubel, Jul 28 2016 *) PROG (MAGMA) [1] cat [ (10*2^n+2*(-1)^n)/3: n in [1..30] ]; (PARI) a(n) = if(n, (10<

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Last modified May 13 19:36 EDT 2021. Contains 343868 sequences. (Running on oeis4.)