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 A215657 #8 Feb 18 2017 13:02:21 %S A215657 65,5691884464123,2171769991015128035203320, %T A215657 1634465653492219202324217583600006782459921190308836446038375668451525 %N A215657 Solution S of (2*u)^2 = R^2 - p*S^2, where p is the n-th prime of the form 4k+1. %C A215657 p = A002144(n), u = A215615(p), and R = A215656(n). %C A215657 A215615 is computed from Wendt's circulant determinant A048954. %C A215657 Brown and Chamberland (2012, p. 600) give explicit formulas for u, R, S. %H A215657 Ezra Brown and Marc Chamberland, <a href="http://www.jstor.org/stable/10.4169/amer.math.monthly.119.07.597">Generalizing Gauss's gem</a>, Amer. Math. Monthly, 119 (Aug. 2012), 597-601. %F A215657 a(n) = sqrt((R^2 - 4*u^2)/p) with R = A215656(n), p = A002144(n), u = A215615(p). %e A215657 2*A215615(5) = 2*11 = 22 and 22^2 = 147^2 - 5*65^2, so a(1) = 65. %Y A215657 Cf. A002144, A048954, A215615, A215656. %K A215657 nonn %O A215657 1,1 %A A215657 _Jonathan Sondow_, Aug 20 2012