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 A355142 #32 Mar 03 2023 16:26:49
%S A355142 33647,100943,302831,908495,2725487,8176463,24529391,73588175,
%T A355142 220764527,662293583,1986880751,5960642255,17881926767,53645780303,
%U A355142 160937340911,482812022735,1448436068207,4345308204623,13035924613871,39107773841615,117323321524847,351969964574543
%N A355142 a(n) = 33648*3^n - 1.
%C A355142 For n > 0, this is the trajectory of 100943 under the map x -> 3*x+2.
%C A355142 100943 is the least starting value > 0 where the trajectory under the map in the previous comment does not reach a prime after a small number of steps.
%C A355142 Are there any primes > 100943 in the sequence (cf. A354747 and A354748)?
%H A355142 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (4,-3).
%F A355142 G.f.: (33647 - 33645*x)/((1 - x)*(1 - 3*x)). - _Stefano Spezia_, Jun 21 2022
%t A355142 33648*3^Range[0,30]-1 (* or *) LinearRecurrence[{4,-3},{33647,100943},30] (* _Harvey P. Dale_, Mar 03 2023 *)
%o A355142 (PARI) a(n) = 33648*3^n-1
%o A355142 (Python)
%o A355142 a = [33647]; [a.append(3*a[-1]+2) for n in range(21)]
%o A355142 print(a) # _Michael S. Branicky_, Jun 20 2022
%Y A355142 Cf. A016789, A052333, A354747, A354748.
%K A355142 nonn,easy
%O A355142 0,1
%A A355142 _Felix Fröhlich_, Jun 20 2022