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Numbers x such that x^2 - 28*y^2 = 1 for some integer y.
2

%I #21 Jun 13 2015 00:53:30

%S 1,127,32257,8193151,2081028097,528572943487,134255446617601,

%T 34100354867927167,8661355881006882817,2199950293420880308351,

%U 558778713173022591438337,141927593195654317345029247

%N Numbers x such that x^2 - 28*y^2 = 1 for some integer y.

%C This sequence gives the values of x in solutions of the Pell equation x^2 - 28*y^2 = 1; the corresponding y values are in A175672. [Edited by _Jon E. Schoenfield_, May 04 2014]

%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (254,-1).

%F a(n) = 254*a(n-1) - a(n-2) (with a(1)=1, a(2)=127).

%F G.f.: x*(1-127*x)/(1-254*x+x^2). - _Bruno Berselli_, Apr 18 2011

%Y Cf. A175672.

%Y Row 8 of array A188644.

%K nonn

%O 1,2

%A _Vincenzo Librandi_, Dec 04 2010