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 A255248 #10 Jun 02 2025 11:41:09
%S A255248 4,7,6,10,9,8,16,11,10,15,19,14,13,22,17,16,14,24,19,28,16,27,22,31,
%T A255248 21,26,20,19,24,29,37,21,20,32,36,31,25,30,23,22,43,29,34,28,38,42,25,
%U A255248 45,49,29,40,35,28,27,34,39,52,43,42,28,36,46,41,35,33,32
%N A255248 Fundamental positive solution y = y2(n) of the second class of the Pell equation x^2 - 2*y^2 = -A001132(n), n>=1 (primes congruent to {1,7} mod 8).
%C A255248 For the corresponding term x2(n) see A255247(n).
%C A255248 See the comments on A255247.
%F A255248 A255247(n)^2 - 2*a(n)^2 = -A001132(n), n >= 1, gives the second smallest positive (proper) solution of this (generalized) Pell equation.
%F A255248 a(n) = -(2*A255235(n+1) - 3*A255246(n+1)), n >= 1.
%e A255248 See A255247.
%e A255248 a(4) = -(2*1 - 3*4) = 12 - 2 = 10.
%e A255248 n=4: 13^2 - 2*10^2 = 169 - 200 = -31 = -A001132(4).
%Y A255248 Cf. A001132, A255247, A255235, A255246, A254937, A255234, A254931.
%K A255248 nonn,easy
%O A255248 1,1
%A A255248 _Wolfdieter Lang_, Feb 19 2015
%E A255248 More terms from _Colin Barker_, Feb 26 2015