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%I #19 Sep 08 2022 08:44:54
%S 1,21,883,18564,780571,16410555,690023881,14506912056,609980330233,
%T 12824093846949,539221921902091,11336484453790860,476671568981118211,
%U 10021439433057273291,421377127757386596433,8858941122338175798384
%N Denominators of continued fraction convergents to sqrt(443).
%H Vincenzo Librandi, <a href="/A041843/b041843.txt">Table of n, a(n) for n = 0..200</a>
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0, 884, 0, -1).
%F G.f.: -(x^2-21*x-1) / (x^4-884*x^2+1). - _Colin Barker_, Nov 25 2013
%F a(n) = 884*a(n-2) - a(n-4) for n>3. - _Vincenzo Librandi_, Dec 25 2013
%t Denominator[Convergents[Sqrt[443], 30]] (* _Vincenzo Librandi_, Dec 25 2013 *)
%o (Magma) I:=[1,21,883,18564]; [n le 4 select I[n] else 884*Self(n-2)-Self(n-4): n in [1..50]]; // _Vincenzo Librandi_, Dec 25 2013
%Y Cf. A041842, A040421.
%K nonn,frac,easy,less
%O 0,2
%A _N. J. A. Sloane_.
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