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 A066420 #12 May 13 2020 19:01:13 %S A066420 1,3,5,15,13,51,37,41,35,65,187,397,2269,1059,313,73,337,247,937,185, %T A066420 689,1139,2057,403,2827,485,323,1321,3697,241,769,9001,433,7129,4201, %U A066420 527,577,1297,1201,15937,3313,3281,3379,949,3121,7519,3889,779,1763 %N A066420 Least m such that card(invphi(phi(m)))=n. %H A066420 T. D. Noe, <a href="/A066420/b066420.txt">Table of n, a(n) for n = 2..1023</a> %F A066420 a(n) = A049283(A007374(n)). - _Max Alekseyev_, Apr 12 2005 %Y A066420 Cf. A049283, A007374. %Y A066420 Cf. A224531, A224532. %K A066420 nonn %O A066420 2,2 %A A066420 _Vladeta Jovovic_, Dec 25 2001 %E A066420 More terms from _Max Alekseyev_, Apr 12 2005