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Denominators of continued fraction convergents to sqrt(171).
2

%I #16 Sep 08 2022 08:44:54

%S 1,13,339,4420,115259,1502787,39187721,510943160,13323709881,

%T 173719171613,4530022171819,59064007405260,1540194214708579,

%U 20081588798616787,523661502978745041,6827681127522302320,178043370818558605361,2321391501768784172013

%N Denominators of continued fraction convergents to sqrt(171).

%H Vincenzo Librandi, <a href="/A041315/b041315.txt">Table of n, a(n) for n = 0..200</a>

%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (0,340,0,-1).

%F G.f.: -(x^2-13*x-1) / (x^4-340*x^2+1). - _Colin Barker_, Nov 15 2013

%F a(n) = 340*a(n-2) - a(n-4). - _Vincenzo Librandi_, Dec 15 2013

%t Denominator[Convergents[Sqrt[171], 30]] (* _Vincenzo Librandi_, Dec 15 2013 *)

%t LinearRecurrence[{0,340,0,-1},{1,13,339,4420},20] (* _Harvey P. Dale_, Aug 05 2014 *)

%o (Magma) I:=[1,13,339,4420]; [n le 4 select I[n] else 340*Self(n-2)-Self(n-4): n in [1..40]]; // _Vincenzo Librandi_, Dec 15 2013

%Y Cf. A041314, A040157.

%K nonn,frac,easy

%O 0,2

%A _N. J. A. Sloane_.

%E More terms from _Colin Barker_, Nov 15 2013