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%I #10 Nov 22 2015 15:27:27
%S 2,45,4,235,118521,6,156,665,8,410581,1431,1464,10,217061235,2629,
%T 20578212225,12,143681684300109,88,4355,53946009001,14,
%U 4149148875801021,244,6705,108,30839304871,16,103789115,78990793279586649,9775,2068,138751721731,18,7987764,2984191388685,13661,5246209297401255,406200,5142295
%N One-half of the x member of the positive proper fundamental solution (x = x2(n), y = y2(n)) of the second class for the Pell equation x^2 - D(n)*y^2 = +8 for even D(n) = A264354(n).
%C The corresponding y2(n) value is given by A264439(n). The positive fundamental solution (x1(n), y1(n)) of the first class is given by (2*A261247(n), A261248(n)).
%C There is only one class of proper solutions for those D = D(n) = A264354(n) that lead to (x1(n), y1(n)) = (x2(n), y2(n)).
%C See A264354 for comments and examples.
%e n=2: D(2) = 28, (2*45)^2 - 28*17^2 = +8. The first class solution was (2*3)^2 - 28*1^2 = +8. This is a D case with two classes of proper solutions.
%e n=3: D(3) = 56, (2*4)^2 - 56*1^2 = +8. The first class has the same solution, therefore this D has only one class of proper solutions.
%Y Cf. A264354, A261247, A261248, A264439, A263012 (odd D), A264349, A264350, A264351, A264353.
%K nonn
%O 1,1
%A _Wolfdieter Lang_, Nov 19 2015
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