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 A199108 #28 May 07 2025 14:57:01
%S A199108 5,13,37,109,325,973,2917,8749,26245,78733,236197,708589,2125765,
%T A199108 6377293,19131877,57395629,172186885,516560653,1549681957,4649045869,
%U A199108 13947137605,41841412813,125524238437,376572715309,1129718145925,3389154437773,10167463313317,30502389939949
%N A199108 a(n) = 4*3^n + 1.
%C A199108 An Engel expansion of 3/4 to the base 3 as defined in A181565, with the associated series expansion 3/4 = 3/5 + 3^2/(5*13) + 3^3/(5*13*37) + 3^4/(5*13*37*109) + .... - _Peter Bala_, Oct 29 2013
%H A199108 Vincenzo Librandi, <a href="/A199108/b199108.txt">Table of n, a(n) for n = 0..1000</a>
%H A199108 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (4,-3).
%F A199108 a(n) = 3*a(n-1) - 2.
%F A199108 a(n) = 4*a(n-1) - 3*a(n-2).
%F A199108 G.f.: (5-7*x)/((1-x)*(1-3*x)). - _Bruno Berselli_, Nov 03 2011
%F A199108 E.g.f.: exp(x)*(1 + 4*exp(2*x)). - _Elmo R. Oliveira_, May 07 2025
%t A199108 4*3^Range[0,30]+1 (* or *) LinearRecurrence[{4,-3},{5,13},30] (* or *) NestList[3#-2&,5,30] (* _Harvey P. Dale_, Mar 01 2012 *)
%o A199108 (Magma) [4*3^n+1 : n in [0..30]];
%Y A199108 Cf. A181565.
%K A199108 nonn,easy
%O A199108 0,1
%A A199108 _Vincenzo Librandi_, Nov 03 2011