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%I #17 Sep 08 2022 08:44:54
%S 1,1,3,4,155,159,473,632,24489,25121,74731,99852,3869107,3968959,
%T 11807025,15775984,611294417,627070401,1865435219,2492505620,
%U 96580648779,99073154399,294726957577,393800111976,15259131212665,15652931324641,46564993861947
%N Denominators of continued fraction convergents to sqrt(390).
%H Vincenzo Librandi, <a href="/A041741/b041741.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 (0,0,0,158,0,0,0,-1).
%F G.f.: -(x^2-x-1)*(x^4+4*x^2+1) / (x^8-158*x^4+1). - _Colin Barker_, Nov 23 2013
%F a(n) = 158*a(n-4) - a(n-8) for n>7. - _Vincenzo Librandi_, Dec 23 2013
%t Denominator[Convergents[Sqrt[390], 30]] (* _Vincenzo Librandi_, Dec 23 2013 *)
%t LinearRecurrence[{0,0,0,158,0,0,0,-1},{1,1,3,4,155,159,473,632},30] (* _Harvey P. Dale_, Aug 06 2015 *)
%o (Magma) I:=[1,1,3,4,155,159,473,632]; [n le 8 select I[n] else 158*Self(n-4)-Self(n-8): n in [1..40]]; // _Vincenzo Librandi_, Dec 23 2013
%Y Cf. A041740, A040370.
%K nonn,frac,easy
%O 0,3
%A _N. J. A. Sloane_.
%E More terms from _Colin Barker_, Nov 23 2013