A042701 - OEIS

%I #20 Sep 08 2022 08:44:55

%S 1,1,2,3,176,179,355,534,31327,31861,63188,95049,5576030,5671079,

%T 11247109,16918188,992502013,1009420201,2001922214,3011342415,

%U 176659782284,179671124699,356330906983,536002031682,31444448744539,31980450776221,63424899520760

%N Denominators of continued fraction convergents to sqrt(880).

%H Vincenzo Librandi, <a href="/A042701/b042701.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 (0,0,0,178,0,0,0,-1).

%F G.f.: -(x^2-x-1)*(x^4+3*x^2+1) / (x^8-178*x^4+1). - _Colin Barker_, Dec 21 2013

%F a(n) = 178*a(n-4) - a(n-8) for n>7. - _Vincenzo Librandi_, Dec 21 2013

%t Denominator[Convergents[Sqrt[880], 30]] (* _Vincenzo Librandi_ Dec 21 2013 *)

%t LinearRecurrence[{0,0,0,178,0,0,0,-1},{1,1,2,3,176,179,355,534},30] (* _Harvey P. Dale_, Dec 09 2018 *)

%o (Magma) I:=[1,1,2,3,176,179,355,534]; [n le 8 select I[n] else 178*Self(n-4)-Self(n-8): n in [1..70]]; // _Vincenzo Librandi_, Dec 21 2013

%Y Cf. A042700, A040850.

%K nonn,frac,easy

%O 0,3

%A _N. J. A. Sloane_.

%E More terms from _Colin Barker_, Dec 21 2013