A174752 - OEIS

%I #11 Sep 08 2022 08:45:51

%S 1,2049,8396801,34410088449,141012534067201,577869330197301249,

%T 2368108374136006451201,9704507539340024239720449,

%U 39769069528107045198367948801,162973637221675131882887614466049

%N x-values in the solution to x^2-41*y^2=1.

%C The corresponding values of y of this Pell equation are in A174778.

%H Vincenzo Librandi, <a href="/A174752/b174752.txt">Table of n, a(n) for n = 1..200</a>

%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (4098,-1).

%F a(n) = 4098*a(n-1)-a(n-2) with a(1)=1, a(2)=2049.

%F G.f.: x*(1-2049*x)/(1-4098*x+x^2).

%t LinearRecurrence[{4098,-1},{1,2049},30]

%o (Magma) I:=[1, 2049]; [n le 2 select I[n] else 4098*Self(n-1)-Self(n-2): n in [1..20]];

%Y Cf. A174778.

%K nonn,easy

%O 1,2

%A _Vincenzo Librandi_, Apr 13 2010