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 A186106 #41 Oct 08 2022 10:48:01
%S A186106 0,1,2,3,5,6,9,12,13,24,41,71,140,189,190,630,713,1066,1173,1202,1271,
%T A186106 1520,1606,2091,2162,2547,6253,7284,8676,10735,12954,22042,32457,
%U A186106 36693,50715,72313
%N A186106 Numbers k such that 3*6^k - 1 is prime.
%C A186106 a(37) > 1*10^5. - _Tyler NeSmith_, Oct 03 2022
%t A186106 lst={}; Do[If[PrimeQ[(3*6^n-1)], Print[n]; AppendTo[lst, n]], {n, 10^5}];
%o A186106 (PARI) is(n)=ispseudoprime(3*6^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y A186106 See A186104 for the actual primes; cf. A185167.
%K A186106 nonn,more
%O A186106 1,3
%A A186106 _Gilbert Mozzo_, Feb 12 2011
%E A186106 a(17)-a(25) computed by _Bruno Berselli_, Feb 12 2011 and Feb 21 2011
%E A186106 a(26)-a(33) computed by _Gilbert Mozzo_, Nov 16 2011 with Mathematica
%E A186106 a(34)-a(35) computed by _Gilbert Mozzo_, Nov 08 2018 with PARI
%E A186106 a(36) from _Tyler NeSmith_, Oct 03 2022