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 A086928 #15 Sep 25 2023 22:48:02
%S A086928 2,12,146,1764,21314,257532,3111698,37597908,454286594,5489037036,
%T A086928 66322731026,801361809348,9682664443202,116993335127772,
%U A086928 1413602685976466,17080225566845364,206376309488120834
%N A086928 a(n) = 12*a(n-1) + a(n-2), with a(0) = 2 and a(1) = 12.
%C A086928 a(n+1)/a(n) converges to (6+sqrt(37)) = 12.0827625... a(0)/a(1)=2/12; a(1)/a(2)=12/146; a(2)/a(3)=146/1764; a(3)/a(4)=1764/21314; ... etc.
%C A086928 Lim_{n->infinity} a(n)/a(n+1) = 0.0827625... = 1/(6+sqrt(37)) = sqrt(37) - 6.
%H A086928 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H A086928 <a href="/index/Rea#recur1">Index entries for recurrences a(n) = k*a(n - 1) +/- a(n - 2)</a>
%H A086928 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (12,1).
%F A086928 a(n) = (6+sqrt(37))^n + (6-sqrt(37))^n.
%F A086928 G.f.: (2-12*x)/(1-12*x-x^2). - _Philippe Deléham_, Nov 21 2008
%e A086928 a(4) = 21314 = 12*a(3) + a(2) = 12*1764 + 146 = (6+sqrt(37))^4 + (6-sqrt(37))^4 = 21313.999953 + 0.000047 = 21314.
%t A086928 LinearRecurrence[{12,1},{2,12},20] (* _Harvey P. Dale_, Oct 31 2016 *)
%Y A086928 Cf. A001927.
%K A086928 easy,nonn
%O A086928 0,1
%A A086928 Nikolay V. Kosinov (kosinov(AT)unitron.com.ua), Sep 21 2003