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 A087619 #17 Jan 25 2020 02:03:18
%S A087619 2,137,18771,2571764,352350439,48274581907,6613970071698,
%T A087619 906162174404533,124150831863492719,17009570127472907036,
%U A087619 2330435258295651756651,319286639956631763568223
%N A087619 a(n) = 137*a(n-1) + a(n-2), with a(0) = 2 and a(1) = 137.
%C A087619 a(n+1)/a(n) converges to (137+sqrt(18773))/2 = 137.00729888121410965...
%C A087619 a(0)/a(1) = 2/137;
%C A087619 a(1)/a(2) = 137/18771;
%C A087619 a(2)/a(3) = 18771/2571764;
%C A087619 a(3)/a(4) = 2571764/352350439; ... etc.
%C A087619 Lim_{n->infinity} a(n)/a(n+1) = 0.00729888121410965... = 2/(137+sqrt(18773)) = (sqrt(18773)-137)/2.
%H A087619 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H A087619 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (137,1).
%F A087619 a(n) = ((137+sqrt(18773))/2)^n + ((137-sqrt(18773))/2)^n.
%F A087619 (a(n))^2 = a(2*n)-2 if n = 1, 3, 5, ..., (a(n))^2 = a(2n) + 2 if n = 2, 4, 6, ...
%F A087619 G.f.: (2-137*x)/(1-137*x-x^2). - _Philippe Deléham_, Nov 23 2008
%Y A087619 Cf. A037088, A073481.
%K A087619 easy,nonn
%O A087619 0,1
%A A087619 Nikolay V. Kosinov (kosinov(AT)unitron.com.ua), Oct 25 2003