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 A136488 a(n) = 2^n - A005418(n). 2
 1, 2, 5, 10, 22, 44, 92, 184, 376, 752, 1520, 3040, 6112, 12224, 24512, 49024, 98176, 196352, 392960, 785920, 1572352, 3144704, 6290432, 12580864, 25163776, 50327552, 100659200, 201318400, 402644992, 805289984, 1610596352, 3221192704, 6442418176, 12884836352 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Colin Barker, Table of n, a(n) for n = 1..1000 Index entries for linear recurrences with constant coefficients, signature (2,2,-4). FORMULA a(n) = 2^n - A005418(n). Sum of (n-1)-th row terms of triangle A136482. G.f.: x*(1 - x^2)/(1 - 2*x - 2*x^2 + 4*x^3). - Michael De Vlieger, Sep 23 2016 From Colin Barker, Sep 23 2016: (Start) a(n) = 3*2^(n-2)-2^(n/2-1) for n even. a(n) = 3*2^(n-2)-2^((n-3)/2) for n odd. (End) a(n) = A135098(n-1) for n >= 1. - Georg Fischer, Nov 02 2018 EXAMPLE a(5) = 22 = 2^5 - A005418(5) = 32 - 10. a(5) = 22 = sum of row 5 terms of triangle A136482 = (1 + 6 + 8 + 6 + 1). MATHEMATICA Table[2^n - (2^(n - 2) + 2^(Floor[n/2] - 1)), {n, 40}] (* after Harvey P. Dale at A005418, or *) CoefficientList[Series[(1 - x^2)/(1 - 2 x - 2 x^2 + 4 x^3), {x, 0, 40}], x] (* Michael De Vlieger, Sep 23 2016 *) PROG (PARI) Vec(x*(1-x)*(1+x)/((1-2*x)*(1-2*x^2)) + O(x^40)) \\ Colin Barker, Sep 23 2016 (MAGMA) [2^n - (2^(n - 2) + 2^(Floor(n/2) - 1)): n in [1..40]]; // G. C. Greubel, Nov 02 2018 CROSSREFS Cf. A005418, A135098, A136482. Sequence in context: A093370 A094537 A135098 * A045621 A026655 A336484 Adjacent sequences:  A136485 A136486 A136487 * A136489 A136490 A136491 KEYWORD nonn,easy AUTHOR Gary W. Adamson, Jan 01 2008 EXTENSIONS More terms from Colin Barker, Mar 19 2013 Missing a(4) added by Michael De Vlieger, Sep 23 2016 STATUS approved

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Last modified November 28 16:34 EST 2021. Contains 349413 sequences. (Running on oeis4.)