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 A227139 #11 Jun 13 2015 00:54:42
%S A227139 1,48,2303,110496,5301505,254361744,12204062207,585540624192,
%T A227139 28093745899009,1347914262528240,64671790855456511,
%U A227139 3102898046799384288,148874434455514989313,7142869955817920102736,342708883444804649942015
%N A227139 Chebyshev S-polynomial evaluated at x = 48.
%C A227139 This sequence, with a(-1) = 0, appears in the solution of the Pell equation u^2 - 23*v^2 = +1 for the solutions v = 5*a(n), n >= -1, together with u = A114051(n+1).
%H A227139 <a href="/index/Ch#Cheby">Index entries for sequences related to Chebyshev polynomials.</a>
%H A227139 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (48,-1).
%F A227139 a(n) = S(n, 48), with the Chebyshev S-polynomial, with coefficients given in A049310.
%F A227139 a(n) = 48*a(n-1) - a(n-2), n >= 1, a(-1) = 0, a(0) = 1.
%F A227139 O.g.f.: 1/(1 - 48*x + x^2).
%F A227139 a(n) = A174767(n+2)/5, n >= 0.
%t A227139 LinearRecurrence[{48,-1},{1,48},20] (* _Harvey P. Dale_, Aug 26 2013 *)
%Y A227139 Cf. A049310, A114051, A174767.
%K A227139 nonn,easy
%O A227139 0,2
%A A227139 _Wolfdieter Lang_, Jul 02 2013