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A098848 a(n) = n*(n + 14). 19

%I #38 Jan 15 2021 07:37:58

%S 0,15,32,51,72,95,120,147,176,207,240,275,312,351,392,435,480,527,576,

%T 627,680,735,792,851,912,975,1040,1107,1176,1247,1320,1395,1472,1551,

%U 1632,1715,1800,1887,1976,2067,2160,2255,2352,2451,2552,2655,2760,2867

%N a(n) = n*(n + 14).

%H G. C. Greubel, <a href="/A098848/b098848.txt">Table of n, a(n) for n = 0..1000</a>

%H 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 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).

%F a(n) = (n+7)^2 - 7^2 = n*(n + 14), n>=0.

%F G.f.: x*(15 - 13*x)/(1-x)^3.

%F a(n) = 2*n + a(n-1) + 13 (with a(0)=0). - _Vincenzo Librandi_, Nov 16 2010

%F Sum_{n>=1} 1/a(n) = 1171733/5045040 = 0.2322544518... via Sum_{n>=0} 1/((n+x)(n+y)) = (psi(x)-psi(y))/(x-y). - _R. J. Mathar_, Jul 14 2012

%F From _G. C. Greubel_, Jul 29 2016: (Start)

%F a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).

%F E.g.f.: x*(15 + x)*exp(x). (End)

%F Sum_{n>=1} (-1)^(n+1)/a(n) = 237371/5045040. - _Amiram Eldar_, Jan 15 2021

%t Table[ n(n + 14), {n, 0, 50}] (* _Robert G. Wilson v_, Jul 14 2005 *)

%t LinearRecurrence[{3, -3, 1}, {0, 15, 32}, 50] (* _G. C. Greubel_, Jul 29 2016 *)

%o (PARI) a(n)=n*(n+14) \\ _Charles R Greathouse IV_, Sep 24 2015

%Y Cf. A098832.

%Y a(n-7), n>=8, seventh column (used for the n=7 series of the hydrogen atom) of triangle A120070.

%K nonn,easy

%O 0,2

%A Eugene McDonnell (eemcd(AT)mac.com), Nov 04 2004

%E More terms from _Robert G. Wilson v_, Jul 14 2005

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