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 A174745 #13 Sep 08 2022 08:45:51
%S A174745 0,12,1320,145188,15969360,1756484412,193197315960,21249948271188,
%T A174745 2337301112514720,257081872428348012,28276668666005766600,
%U A174745 3110176471388205977988,342091135184036651812080
%N A174745 y-values in the solution to x^2 - 21*y^2 = 1.
%C A174745 The corresponding values of x of this Pell equation are in A114049.
%H A174745 Vincenzo Librandi, <a href="/A174745/b174745.txt">Table of n, a(n) for n = 1..200</a>
%H A174745 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (110,-1).
%F A174745 a(n) = 110*a(n-1)-a(n-2) with a(1)=0, a(2)=12.
%F A174745 G.f.: 12*x^2/(1-110*x+x^2).
%t A174745 LinearRecurrence[{110,-1},{0,12},30]
%o A174745 (Magma) I:=[0, 12]; [n le 2 select I[n] else 110*Self(n-1)-Self(n-2): n in [1..20]];
%Y A174745 Cf. A114049.
%K A174745 nonn,easy
%O A174745 1,2
%A A174745 _Vincenzo Librandi_, Apr 14 2010