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%I #22 Sep 08 2022 08:44:54
%S 1,4,129,520,16769,67596,2179841,8786960,283362561,1142237204,
%T 36834953089,148482049560,4788260539009,19301524205596,
%U 622437035118081,2509049664677920,80912026304811521,326157154883924004,10517940982590379649,42397921085245442600
%N Denominators of continued fraction convergents to sqrt(264).
%H Vincenzo Librandi, <a href="/A041495/b041495.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 (0,130,0,-1).
%F G.f.: (1+4*x-x^2)/(1-130*x^2+x^4). - _Colin Barker_, Nov 18 2013
%F a(n) = 130*a(n-2) - a(n-4) for n>3. - _Vincenzo Librandi_, Dec 18 2013
%F a(2n) = A041115(2n), a(2n+1) = A041115(2n+1)/2. - _M. F. Hasler_, Feb 24 2020
%t Denominator[Convergents[Sqrt[264], 30]] (* _Vincenzo Librandi_, Dec 18 2013 *)
%o (Magma) I:=[1,4,129,520]; [n le 4 select I[n] else 130*Self(n-2)-Self(n-4): n in [1..30]]; // _Vincenzo Librandi_, Dec 18 2013
%o (PARI) apply( {A041495(n)=([130,-1;1,0]^(n\2))[1,]*[4^n%=2,1-n]~}, [0..20]) \\ _M. F. Hasler_, Feb 24 2020
%Y Cf. A040247, A041115, A041494.
%K nonn,frac,easy
%O 0,2
%A _N. J. A. Sloane_
%E More terms from _Colin Barker_, Nov 18 2013
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