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A328858
Numbers with a record number of distinct values of the Euler totient function applied to their divisors (A319696).
4
1, 3, 8, 15, 32, 45, 72, 105, 144, 216, 288, 432, 792, 864, 1296, 1584, 1728, 2376, 2592, 3168, 4752, 9504, 14256, 19008, 28512, 38016, 54000, 57024, 85536, 108000, 114048, 162000, 171072, 216000, 218592, 228096, 324000, 342144, 437184, 465696, 648000, 655776
OFFSET
1,2
COMMENTS
The corresponding record values are 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 16, 17, 18, 19, 20, 21, 22, 26, 32, 34, 38, 42, 44, 45, 50, 52, 54, 58, 59, 62, 63, 64, 66, 71, 72, 76, 78, 83, 84, ...
LINKS
EXAMPLE
The first 10 terms of A319696(k) are 1, 1, 2, 2, 2, 2, 2, 3, 3, 2. The record values 1, 2, and 3 are obtained at k = 1, 3, and 8. Therefore this sequence begins with 1, 3, 8.
MATHEMATICA
f[n_] := Length @ Union[EulerPhi /@ Divisors[n]]; fm = 0; s = {}; Do[f1 = f[n]; If[f1 > fm, fm = f1; AppendTo[s, n]], {n, 1, 660000}]; s
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Oct 28 2019
STATUS
approved