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%I #15 Sep 08 2022 08:44:55
%S 29,59,3451,6961,407189,821339,48044851,96911041,5668885229,
%T 11434681499,668880412171,1349195505841,78922219750949,
%U 159193635007739,9312153050199811,18783499735407361,1098755137703826749
%N Numerators of continued fraction convergents to sqrt(870).
%H Vincenzo Librandi, <a href="/A042680/b042680.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 (0,118,0,-1).
%F G.f.: (29 +59*x +29*x^2 -x^3)/(1 -118*x^2 +x^4). - _Vincenzo Librandi_, Dec 01 2013
%F a(n) = 118*a(n-2) - a(n-4). - _Vincenzo Librandi_, Dec 01 2013
%t Numerator[Convergents[Sqrt[870], 30]] (* _Harvey P. Dale_, Oct 11 2012 *)
%t CoefficientList[Series[(29 + 59 x + 29 x^2 - x^3)/(1 - 118 x^2 + x^4), {x, 0, 30}], x] (* _Vincenzo Librandi_, Dec 01 2013 *)
%o (Magma) I:=[29,59,3451,6961]; [n le 4 select I[n] else 118*Self(n-2)-Self(n-4): n in [1..30]]; // _Vincenzo Librandi_, Dec 01 2013
%Y Cf. A042681.
%K nonn,cofr,frac,easy
%O 0,1
%A _N. J. A. Sloane_.
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