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 A262028 #5 Oct 05 2015 03:15:15 %S A262028 0,1,0,1,0,19,2,0,2,136,1,0,1,265,3,0,3,34,0,2983,206,1,4,0,4,1,10,82, %T A262028 2,0,11209,2,46,52,5,0,5,209887,25,463,10,1,3289414,0,70317346,1,52, %U A262028 28,2509567,6,0,6,76,7,156595 %N A262028 a(n) = (A262026(n) - 1)/2. %C A262028 This is the column Y_0 of the Table of a proof given as a W. Lang link under A007970. %C A262028 (x0(n), y0(n) = 2*a(n) + 1) with x0(n) = A262067(n) are the fundamental solutions of the Pell equation x^2 - d*y^2 = +1 with odd y. The d values coincide with d = d(n) = A007970(n). For a proof see the mentioned link. %F A262028 A262067(n)^2 - A007970(n)*(2*a(n) + 1)^2 = +1, n >= 1. %e A262028 For the first triples [d(n), x0(n), 2*a(n) + 1] see A262066. %Y A262028 Cf. A006970, A262026, A262067. %K A262028 nonn %O A262028 1,6 %A A262028 _Wolfdieter Lang_, Oct 04 2015