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 A171938 #11 Jul 30 2023 09:21:46
%S A171938 1,4,5,8,21,22,24,29,60,61,72,73,97,100,184,216,239,451,469
%N A171938 Record values in A138753 (a "prime" variation of the Collatz (3n+1) problem).
%F A171938 A171938(n) = A138753(A138756(n)).
%F A171938 A171938 = { A138753(m) | A138753(k) < A138753(m) for all k<m }.
%t A171938 A138754[n_]:=A138754[n]=With[{p=Prime[n]},PrimePi[NextPrime[If[Mod[p,3]==2,p/2,2p]]]];
%t A171938 A138753[n_]:=Length[NestWhileList[A138754,n,UnsameQ,{1,4}]]-1;
%t A171938 A171938list[upto_]:=Module[{v,r=0},Table[If[(v=A138753[n])>r,r=v,Nothing],{n,upto}]];
%t A171938 A171938list[500] (* _Paolo Xausa_, Jul 29 2023 *)
%o A171938 (PARI) m=0; for( i=1,#A138753, A138753[i] > m & print1( m=A138753[i],", "))
%Y A171938 Cf. A124123, A138750-A138754, A138756, A006878 (analog for Collatz problem).
%K A171938 nonn,hard,more
%O A171938 1,2
%A A171938 _M. F. Hasler_, Apr 01 2008
%E A171938 Originally submitted as A138755, but mislaid by Editor-in-Chief; renumbered and added to OEIS, Oct 24 2010
%E A171938 a(15)-a(19) from _Paolo Xausa_, Jul 29 2023