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 A069229 #25 May 06 2021 15:28:33
%S A069229 0,3,10,27,68,165,390,903,2056,4617,10250,22539,49164,106509,229390,
%T A069229 491535,1048592,2228241,4718610,9961491,20971540,44040213,92274710,
%U A069229 192938007,402653208,838860825,1744830490,3623878683,7516192796
%N A069229 a(n) = n*(2^n + 1).
%C A069229 Odd terms are multiples of 3. - _Dario Piazzalunga_, Jan 10 2013
%H A069229 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (6, -13, 12, -4).
%F A069229 Recurrence: a(n) = 6*a(n-1) - 13*a(n-2) + 12*a(n-3) - 4*a(n-4).
%F A069229 G.f.: x*(3 - 8*x + 6*x^2)/(1-x)^2/(1 - 2*x)^2.
%F A069229 a(n) = n+A036289(n). - _R. J. Mathar_, Jun 17 2020
%t A069229 Table[n*2^n+n,{n,0,3*4!}] (* _Vladimir Joseph Stephan Orlovsky_, Apr 25 2010 *)
%t A069229 LinearRecurrence[{6,-13,12,-4},{0,3,10,27},30] (* _Harvey P. Dale_, May 06 2021 *)
%Y A069229 Cf. A066524.
%K A069229 nonn,easy
%O A069229 0,2
%A A069229 _Vladeta Jovovic_, Apr 12 2002