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 A097771 #9 Aug 12 2015 09:15:50
%S A097771 1,678,459683,311664396,211308000805,143266512881394,
%T A097771 97134484425584327,65857037174033292312,44650974069510146603209,
%U A097771 30273294562090705363683390,20525249062123428726430735211
%N A097771 Chebyshev U(n,x) polynomial evaluated at x=339=2*13^2+1.
%C A097771 Used to form integer solutions of Pell equation a^2 - 170*b^2 =-1. See A097772 with A097773.
%H A097771 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H A097771 <a href="/index/Ch#Cheby">Index entries for sequences related to Chebyshev polynomials.</a>
%H A097771 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (678, -1).
%F A097771 a(n) = 2*339*a(n-1) - a(n-2), n>=1, a(0)=1, a(-1):=0.
%F A097771 a(n) = S(n, 2*339)= U(n, 339), Chebyshev's polynomials of the second kind. See A049310.
%F A097771 G.f.: 1/(1-2*339*x+x^2).
%F A097771 a(n)= sum((-1)^k*binomial(n-k, k)*678^(n-2*k), k=0..floor(n/2)), n>=0.
%F A097771 a(n) = ((339+26*sqrt(170))^(n+1) - (339-26*sqrt(170))^(n+1))/(52*sqrt(170)), n>=0.
%t A097771 LinearRecurrence[{678, -1},{1, 678},11] (* _Ray Chandler_, Aug 12 2015 *)
%K A097771 nonn,easy
%O A097771 0,2
%A A097771 _Wolfdieter Lang_, Aug 31 2004