A300079 Composite numbers k such that there are exactly phi(phi(k)) residues modulo k of the maximum order.

4, 6, 9, 10, 14, 15, 16, 18, 20, 22, 25, 26, 27, 30, 32, 34, 35, 38, 39, 40, 45, 46, 48, 49, 50, 51, 52, 54, 55, 58, 60, 62, 64, 68, 70, 74, 75, 78, 81, 82, 85, 86, 87, 90, 94, 95, 96, 98, 100, 102, 104, 105, 106, 110, 111, 112, 115, 116, 118, 119, 120, 121, 122, 123, 125, 128, 134, 135, 136, 140, 142, 143, 144, 146, 148, 150, 153

Offset

1,1

Comments

Composite numbers k such that A111725(k) = A010554(k).

Contains as a subsequence the nontrivial prime powers (A246547) except 2^3 = 8.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

q[n_] := Count[(t = Table[MultiplicativeOrder[k, n], {k, Select[Range[n], CoprimeQ[n, #] &]}]), Max[t]] == EulerPhi[EulerPhi[n]]; Select[Range[150], CompositeQ[#] && q[#] &] (* Amiram Eldar, Oct 12 2021 *)

Crossrefs

Subsequence of A300064.

Set difference of A002808 and A300065.

Contains A300080 as a subsequence.

Cf. A000010, A002322, A010554, A111725, A246547.

Sequence in context: A284654 A010428 A189300 * A233182 A028260 A085155

Adjacent sequences: A300076 A300077 A300078 * A300080 A300081 A300082

Keyword

nonn

Author

Max Alekseyev, Feb 24 2018

Status

approved