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%I #17 Sep 08 2022 08:44:54
%S 1,8,321,2576,103361,829464,33281921,267084832,10716675201,
%T 86000486440,3450736132801,27691889548848,1111126318086721,
%U 8916702434242616,357779223687791361,2871150491936573504,115203798901150731521,924501541701142425672
%N Denominators of continued fraction convergents to sqrt(405).
%H Vincenzo Librandi, <a href="/A041769/b041769.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 (0,322,0,-1).
%F G.f.: -(x^2-8*x-1) / ((x^2-18*x+1)*(x^2+18*x+1)). - _Colin Barker_, Nov 24 2013
%F a(n) = 322*a(n-2) - a(n-4) for n>3. - _Vincenzo Librandi_, Dec 24 2013
%t Denominator[Convergents[Sqrt[405], 30]] (* _Vincenzo Librandi_, Dec 24 2013 *)
%o (Magma) I:=[1,8,321,2576]; [n le 4 select I[n] else 322*Self(n-2)-Self(n-4): n in [1..40]]; // _Vincenzo Librandi_, Dec 24 2013
%Y Cf. A041768, A040384.
%K nonn,frac,easy
%O 0,2
%A _N. J. A. Sloane_.
%E More terms from _Colin Barker_, Nov 24 2013