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%I #13 Sep 08 2022 08:45:51
%S 1,25,1249,62425,3120001,155937625,7793761249,389532124825,
%T 19468812480001,973051091875225,48633085781281249,2430681237972187225,
%U 121485428812828080001,6071840759403431812825,303470552541358762561249
%N x-values in the solution to x^2-39*y^2=1.
%C The corresponding values of y of this Pell equation are in A174776.
%H Vincenzo Librandi, <a href="/A174751/b174751.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 (50,-1).
%F a(n) = 50*a(n-1)-a(n-2) with a(1)=1, a(2)=25.
%F G.f.: x*(1-25*x)/(1-50*x+x^2).
%t LinearRecurrence[{50,-1},{1,25},30]
%t Rest[CoefficientList[Series[x (1-25x)/(1-50x+x^2),{x,0,20}],x]] (* _Harvey P. Dale_, Aug 10 2021 *)
%o (Magma) I:=[1, 25]; [n le 2 select I[n] else 50*Self(n-1)-Self(n-2): n in [1..20]];
%Y Cf. A174776.
%K nonn,easy
%O 1,2
%A _Vincenzo Librandi_, Apr 13 2010
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