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A293714
Numbers k such that phi(phi(k))/k < phi(phi(m))/m for all m < k, where phi is Euler's totient function (A000010).
0
1, 2, 3, 4, 6, 14, 18, 42, 90, 186, 198, 210, 450, 462, 930, 990, 1050, 2310, 7350, 14910, 16170, 66990, 169050, 177870, 371910, 1540770, 2312310, 4626930, 4834830, 19711230, 20030010, 30060030, 60150090, 62852790, 256245990, 260390130, 1061590530, 1068497430
OFFSET
1,2
MATHEMATICA
f[n_] := EulerPhi[EulerPhi[n]]/n; a={}; fm=10^10; Do[f1=f[k]; If[f1<fm , fm=f1; AppendTo[a, k]], {k, 1, 10^6}]; a
PROG
(PARI) lista(nn) = {my(rmin = 2); for (n=1, nn, if ((r=eulerphi(eulerphi(n))/n) < rmin, rmin = r; print1(n, ", ")); ); }
CROSSREFS
Sequence in context: A369849 A174046 A095991 * A049911 A056712 A204540
KEYWORD
nonn,changed
AUTHOR
Amiram Eldar, Oct 15 2017
EXTENSIONS
a(26)-a(34) from Michel Marcus, Oct 18 2017
a(35)-a(38) from Amiram Eldar, Nov 12 2024
STATUS
approved