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 A098248 #12 Feb 09 2017 09:16:12
%S A098248 1,291,84680,24641589,7170617719,2086625114640,607200737742521,
%T A098248 176693328057958971,51417151264128318040,14962214324533282590669,
%U A098248 4353952951287921105566639,1266985346610460508437301280
%N A098248 Chebyshev polynomials S(n,291).
%C A098248 Used for all positive integer solutions of Pell equation x^2 - 293*y^2 = -4. See A098249 with A098250.
%H A098248 Indranil Ghosh, <a href="/A098248/b098248.txt">Table of n, a(n) for n = 0..405</a>
%H A098248 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H A098248 <a href="/index/Ch#Cheby">Index entries for sequences related to Chebyshev polynomials.</a>
%H A098248 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (291,-1).
%F A098248 a(n)= S(n, 291)=U(n, 291/2)= S(2*n+1, sqrt(293))/sqrt(293) with S(n, x)=U(n, x/2) Chebyshev's polynomials of the second kind, A049310. S(-1, x)= 0 = U(-1, x).
%F A098248 a(n)=291*a(n-1)-a(n-2), n >= 1; a(0)=1, a(1)=291; a(-1):=0.
%F A098248 a(n)=(ap^(n+1) - am^(n+1))/(ap-am) with ap := (291+17*sqrt(293))/2 and am := (291-17*sqrt(293))/2 = 1/ap.
%F A098248 G.f.: 1/(1-291*x+x^2).
%t A098248 LinearRecurrence[{291,-1},{1,291},20] (* _Harvey P. Dale_, Dec 27 2015 *)
%K A098248 nonn,easy
%O A098248 0,2
%A A098248 _Wolfdieter Lang_, Sep 10 2004