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 A135522 #30 Sep 08 2022 08:45:32
%S A135522 2,3,12,33,102,303,912,2733,8202,24603,73812,221433,664302,1992903,
%T A135522 5978712,17936133,53808402,161425203,484275612,1452826833,4358480502,
%U A135522 13075441503,39226324512,117678973533,353036920602,1059110761803
%N A135522 a(n) = 2*a(n-1) + 3*a(n-2), with a(0) = 2 and a(1) = 3.
%C A135522 Also: inverse binomial transform of A135520. - _R. J. Mathar_, Apr 17 2008
%H A135522 Vincenzo Librandi, <a href="/A135522/b135522.txt">Table of n, a(n) for n = 0..1000</a>
%H A135522 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,3).
%F A135522 From _R. J. Mathar_, Feb 23 2008: (Start)
%F A135522 O.g.f.: (5/(1-3*x) + 3/(1+x))/4.
%F A135522 a(n) = (5*3^n + 3*(-1)^n)/4. (End)
%F A135522 G.f.: (x-2)/(3*x^2 + 2*x - 1). - _Harvey P. Dale_, Mar 14 2011
%F A135522 E.g.f.: (1/4)*(5*exp(3*x) + 3*exp(-x)). - _G. C. Greubel_, Oct 17 2016
%t A135522 f[n_]:=3/(n+2);x=2;Table[x=f[x];Numerator[x],{n,0,5!}] (* _Vladimir Joseph Stephan Orlovsky_, Mar 11 2010 *)
%t A135522 Transpose[NestList[Join[Rest[#],ListCorrelate[{3,2},#]]&, {2,3},30]][[1]] (* _Harvey P. Dale_, Mar 14 2011 *)
%t A135522 CoefficientList[Series[(x-2)/(3x^2+2x-1),{x,0,30}],x] (* _Harvey P. Dale_, Mar 14 2011 *)
%o A135522 (PARI) a(n)=(5*3^n+3*(-1)^n)/4 \\ _Charles R Greathouse IV_, Jun 01 2011
%o A135522 (Magma) [(5*3^n+3*(-1)^n)/4: n in [0..40]]; // _Vincenzo Librandi_, Jun 02 2011
%Y A135522 Cf. A060925.
%K A135522 nonn,easy
%O A135522 0,1
%A A135522 _Paul Curtz_, Feb 19 2008
%E A135522 More terms from _R. J. Mathar_, Feb 23 2008