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 A024869 a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = floor( n/2 ), s = natural numbers >= 2, t = natural numbers >= 3. 1
 8, 10, 27, 32, 61, 70, 114, 128, 190, 210, 293, 320, 427, 462, 596, 640, 804, 858, 1055, 1120, 1353, 1430, 1702, 1792, 2106, 2210, 2569, 2688, 3095, 3230, 3688, 3840, 4352, 4522, 5091, 5280, 5909, 6118, 6810, 7040, 7798, 8050, 8877, 9152, 10051, 10350, 11324, 11648 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 2..1000 Index entries for linear recurrences with constant coefficients, signature (1,3,-3,-3,3,1,-1) FORMULA G.f.: x^2*(8+2*x-7*x^2-x^3+2*x^4) / ((1+x)^3*(x-1)^4). - R. J. Mathar, Sep 25 2013 a(n) = 8*A058187(n-2) +2*A058187(n-3) -7*A058187(n-4) -A058187(n-5) +2*A058187(n-6). - R. J. Mathar, Sep 25 2013 From Colin Barker, Jan 29 2016: (Start) a(n) = (4*n^3+3*((-1)^n+13)*n^2+4*(6*(-1)^n+17)*n+42*((-1)^n-1))/48. a(n) = (2*n^3+21*n^2+46*n)/24 for n even. a(n) = (2*n^3+18*n^2+22*n-42)/24 for n odd. (End) MATHEMATICA CoefficientList[Series[(8 + 2 x - 7 x^2 - x^3 + 2 x^4)/((1 + x)^3 (x - 1)^4), {x, 0, 50}], x] (* Vincenzo Librandi, Sep 25 2013 *) PROG (PARI) Vec(x^2*(8+2*x-7*x^2-x^3+2*x^4)/((1+x)^3*(x-1)^4) + O(x^100)) \\ Colin Barker, Jan 29 2016 CROSSREFS Sequence in context: A236751 A259713 A096516 * A108940 A007939 A212767 Adjacent sequences: A024866 A024867 A024868 * A024870 A024871 A024872 KEYWORD nonn,easy AUTHOR Clark Kimberling STATUS approved

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Last modified June 5 05:23 EDT 2023. Contains 363130 sequences. (Running on oeis4.)