This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A262027 #12 Oct 21 2015 05:58:05 %S A262027 2,8,3,10,4,170,24,5,26,1520,17,6,19,3482,48,7,50,530,8,48842,3480,26, %T A262027 80,9,82,28,197,1574,49,10,227528,51,962,1126,120,11,122,4730624,577, %U A262027 10610,244,35,77563250,12,1728148040,37,1324,721,64080026,168,13,170,2024,199,4190210 %N A262027 The positive fundamental solutions x = x0(n) for the Pell equation x^2 - d*y^2 = +1 with odd y = y0(n). Then d coincides with d(n) = A007970(n). %C A262027 The corresponding values y = y0(n) are given by A262026(n). %C A262027 This is a proper subset of A033313 corresponding to D values from d(n) = A007970(n). %C A262027 For the proof that d(n) = A007970(n), the products of Conway's 2-happy couples, see the W. Lang link under A007970. %C A262027 If d(n) = A007970(n) is odd (necessarily congruent to 3 modulus 4) then x0(n) is even, and if d(n) is even (necessarily congruent to 0 modulus 8) then x0 is odd. %F A262027 a(n)^2 - d(n)*y0(n)^2 = +1 with y0(n) = A262026(n) and d(n) = A007970(n). (x0(n) = a(n), y0(n)) are the positive fundamental solutions of this Pell equation x^2 - d*y^2 = +1 with odd y = y0. %e A262027 For the first [d(n), x0(n), y0(n)] see A262026. %Y A262027 Cf. A007970, A033313, A262026. %K A262027 nonn %O A262027 1,1 %A A262027 _Wolfdieter Lang_, Oct 04 2015