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%I #11 Apr 01 2019 03:00:34
%S 4,65,1036,16511,263140,4193729,66836524,1065190655,16976213956,
%T 270554232641,4311891508300,68719709900159,1095203466894244,
%U 17454535760407745,278177368699629676,4433383363433667071,70655956446239043460,1126061919776391028289,17946334759976017409164
%N First class of all proper positive solutions y1(n) = a(n) of the Pell equation x^2 - 7*y^2 = 9.
%C The corresponding x1 solutions are given in A307168.
%C For details see A307168.
%H <a href="/index/Ch#Cheby">Index entries for sequences related to Chebyshev polynomials.</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (16,-1).
%F G.f.: x*(4 + x)/(1 - 16*x + x^2).
%F a(n) = -S(n, 16) + 20*S(n-1, 16) for n >= 1, with S(n,16) = A077412(n).
%F a(n) = sqrt((A307168(n)^2 - 9)/7) for n >= 1.
%Y Cf. A077412, A307168.
%K nonn,easy
%O 1,1
%A _Wolfdieter Lang_, Mar 27 2019
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