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 A144928 Values of k arising in A144927. 4
 49, 5341, 587461, 64615369, 7107103129, 781716728821, 85981733067181, 9457208920661089, 1040206999539652609, 114413312740441125901, 12584424194448984196501, 1384172248076647820489209, 152246362864236811269616489, 16745715742817972591837324581 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers k such that there exists x in N : (x+7)^3-x^3=k^2. - Richard Choulet, Oct 16 2008 LINKS Colin Barker, Table of n, a(n) for n = 1..450 Index entries for linear recurrences with constant coefficients, signature (110,-1). FORMULA a(n+2) = 110*a(n+1)-a(n). - Richard Choulet, Oct 16 2008 G.f.: 49*x*(1-x) / (1-110*x+x^2). - Colin Barker, Oct 17 2014, corrected Jul 16 2016 EXAMPLE a(1) = 49 because (7+7)^3 - 7^3 = 2041 = 49^2. - Richard Choulet, Oct 16 2008 a(2) = 5341 because (1162+7)^3 - 1162^3 = 28526281 = 5341^2. - Colin Barker, Jul 16 2016 MATHEMATICA Sqrt[(# + 7)^3 - #^3] & /@ Rest@ CoefficientList[Series[7 x (-1 - 55 x + 2 x^2)/((x - 1) (x^2 - 110 x + 1)), {x, 0, 14}], x] (* or *) Rest@ CoefficientList[Series[49 x (1 - x)/(1 - 110 x + x^2), {x, 0, 14}], x] (* Michael De Vlieger, Jul 17 2016 *) PROG (PARI) Vec(49*x*(1-x)/(1-110*x+x^2) + O(x^20)) \\ Colin Barker, Oct 17 2014, corrected Jul 16 2016 CROSSREFS Cf. A144927. Sequence in context: A109344 A129207 A243944 * A053772 A075416 A127861 Adjacent sequences:  A144925 A144926 A144927 * A144929 A144930 A144931 KEYWORD nonn,easy AUTHOR Richard Choulet, Sep 25 2008 EXTENSIONS More terms from Colin Barker, Oct 17 2014 All terms except the first corrected by Colin Barker, Jul 16 2016 STATUS approved

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Last modified October 15 12:31 EDT 2019. Contains 328026 sequences. (Running on oeis4.)