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A132768 a(n) = n*(n + 26).

%I A132768 #33 Mar 13 2022 03:31:21
%S A132768 0,27,56,87,120,155,192,231,272,315,360,407,456,507,560,615,672,731,
%T A132768 792,855,920,987,1056,1127,1200,1275,1352,1431,1512,1595,1680,1767,
%U A132768 1856,1947,2040,2135,2232,2331,2432,2535,2640,2747,2856,2967,3080,3195,3312,3431
%N A132768 a(n) = n*(n + 26).
%H A132768 G. C. Greubel, <a href="/A132768/b132768.txt">Table of n, a(n) for n = 0..5000</a>
%H A132768 Felix P. Muga II, <a href="https://www.researchgate.net/publication/267327689_Extending_the_Golden_Ratio_and_the_Binet-de_Moivre_Formula">Extending the Golden Ratio and the Binet-de Moivre Formula</a>, Preprint on ResearchGate, March 2014.
%H A132768 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A132768 a(n) = n*(n + 26).
%F A132768 a(n) = 2*n + a(n-1) + 25, with a(0)=0. - _Vincenzo Librandi_, Aug 03 2010
%F A132768 From _Amiram Eldar_, Jan 16 2021: (Start)
%F A132768 Sum_{n>=1} 1/a(n) = H(26)/26 = A001008(26)/A102928(26) = 34395742267/232016584800, where H(k) is the k-th harmonic number.
%F A132768 Sum_{n>=1} (-1)^(n+1)/a(n) = 18051406831/696049754400. (End)
%F A132768 From _G. C. Greubel_, Mar 13 2022: (Start)
%F A132768 G.f.: x*(27 - 25*x)/(1-x)^3.
%F A132768 E.g.f.: x*(27 + x)*exp(x). (End)
%t A132768 Table[n(n+26),{n,0,50}] (* or *) LinearRecurrence[{3,-3,1},{0,27,56},50] (* _Harvey P. Dale_, Dec 15 2018 *)
%o A132768 (PARI) a(n)=n*(n+26) \\ _Charles R Greathouse IV_, Jun 17 2017
%o A132768 (Sage) [n*(n+26) for n in (0..50)] # _G. C. Greubel_, Mar 13 2022
%Y A132768 Cf. A001008, A002378, A005563, A028347, A028552, A028557, A028560, A028563, A028566, A028569.
%Y A132768 Cf. A098849, A098850, A098603, A098847, A098848, A102928, A120071, A132759, A132760, A132761.
%Y A132768 Cf. A132762, A132763, A132764, A132765, A132766, A132767.
%K A132768 nonn,easy
%O A132768 0,2
%A A132768 _Omar E. Pol_, Aug 28 2007