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 A255235 #18 Feb 26 2015 08:11:35
%S A255235 4,1,1,3,1,3,5,1,5,7,3,1,5,7,1,5,7,11,3,7,1,13,3,7,1,9,5,11,13,9,5,1,
%T A255235 15,17,5,3,7,13,9,17,19,1,11,7,13,5,3,19,3,1,17,7,11,19,21,13,9,1,7,9,
%U A255235 25,15,7,11,17,21,23,27,5
%N A255235 Fundamental positive solution x = x1(n) of the first class of the Pell equation x^2 - 2*y^2 = -A038873(n), n>=1 (primes congruent to {1,2,7} mod 8).
%C A255235 For the corresponding term y1(n) see A255246(n).
%C A255235 The present solutions of this first class are the smallest positive ones.
%C A255235 For the positive fundamental proper (sometimes called primitive) solutions x2 and y2 of the second class of this (generalized) Pell equation see A255247 and A255248. There is no second class for prime 2.
%C A255235 For the first class solutions of this Pell equation with primes 1 (mod 8) see A254934 and A254935. For those with primes 7 (mod 8) see A254938 and 2*A255232. For the derivation of these solutions see A254934 and A254938, also for the Nagell reference.
%F A255235 a(n)^2 - A255246(n)^2 = - A038873(n), n >= 1, gives the smallest positive (proper) solution of this (generalized) Pell equation.
%e A255235 The first pairs [x1(n), y1(n)] of the fundamental positive solutions of this first class are
%e A255235 (the prime A038873(n) is listed as first entry):
%e A255235 [2,[4, 3]], [7, [1, 2]], [17, [1, 3]],
%e A255235 [23, [3, 4]], [31, [1, 4]], [41, [3, 5]],
%e A255235 [47, [5, 6]], [71, [1, 6]], [73, [5, 7]],
%e A255235 [79, [7, 8]], [89, [3, 7]], [97, [1, 7]],
%e A255235 [103, [5, 8]], [113, [7, 9]], [127, [1, 8]],
%e A255235 [137, [5, 9]], [151, [7, 10]], [167, [11, 12]], [191, [3, 10]], [193, [7, 11]], [199, [1, 10]], [223, [13, 14]], [233, [3, 11]], [239, [7, 12]], [241, [1, 11]], [257, [9, 13]], [263, [5, 12]], ...
%e A255235 n=1: 4^2 - 2*3^2 = -2 = -A038873(1),
%e A255235 n=2: 1^2 - 2*2^2 = 1 - 8 = -7 = -A038873(2).
%Y A255235 Cf. A038873, A255246, A255247, A255248, A254934, A254935, A254938, 2*A255232, A002334.
%K A255235 nonn,easy
%O A255235 1,1
%A A255235 _Wolfdieter Lang_, Feb 25 2015
%E A255235 More terms from _Colin Barker_, Feb 26 2015