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 A229487 #11 Sep 22 2017 10:12:58
%S A229487 2,6,12,30,22,138,60,54,46,58,62,174,498,510,94,106,118,4314,134,142,
%T A229487 1038,158,166,276,420,250,206,214,750,1758,254,262,274,278,298,302,
%U A229487 1182,486,334,346,358,6360,382,1614,394,398,422,446,454,458,5898,478,54582
%N A229487 Conjectured greatest number that converges to prime(n) under the iteration x -> phi(x) + 1, where phi is Euler's totient function.
%C A229487 Many terms are just twice a prime: 6, 22, 46, 58, 62, 94,....
%H A229487 Donovan Johnson, <a href="/A229487/b229487.txt">Table of n, a(n) for n = 1..1000</a>
%e A229487 The number 138 has trajectory {138, 45, 25, 21, 13}, which is conjecturally the last number that terminates with 13 = prime(6). Hence a(6) = 138.
%t A229487 t = Table[NestWhileList[EulerPhi[#] + 1 &, n, UnsameQ, All][[-1]], {n, 100000}]; Table[Position[t, p][[-1]], {p, Prime[Range[53]]}]
%Y A229487 Cf. A039650, A039651, A039652.
%K A229487 nonn
%O A229487 1,1
%A A229487 _T. D. Noe_, Oct 16 2013