A272593 Numbers n such that the multiplicative group modulo n is the direct product of 3 cyclic groups.

24, 40, 48, 56, 60, 72, 80, 84, 88, 96, 104, 105, 112, 132, 136, 140, 144, 152, 156, 160, 165, 176, 180, 184, 192, 195, 200, 204, 208, 210, 216, 220, 224, 228, 231, 232, 248, 252, 255, 260, 272, 273, 276, 285, 288, 296, 300, 304, 308, 315, 320, 328, 330, 340, 344, 345, 348, 352, 357, 364, 368, 372, 376, 380

Offset

1,1

Comments

Numbers n such that A046072(n) = 3.

Links

Table of n, a(n) for n=1..64.

Mathematica

A046072[n_] := Which[n == 1 || n == 2, 1,
     OddQ[n], PrimeNu[n],
     EvenQ[n] && !Divisible[n, 4], PrimeNu[n] - 1,
     Divisible[n, 4] && !Divisible[n, 8], PrimeNu[n],
     Divisible[n, 8], PrimeNu[n] + 1];
Select[Range[400], A046072[#] == 3&] (* Jean-François Alcover, Dec 22 2021, after Geoffrey Critzer in A046072 *)

Prog

(PARI) for(n=1, 10^3, my(t=#(znstar(n)[2])); if(t==3, print1(n, ", ")));

Crossrefs

Cf. A046072.

Direct product of k groups: A033948 (k=1), A272592 (k=2), A272594 (k=4), A272595 (k=5), A272596 (k=6), A272597 (k=7), A272598 (k=8), A272599 (k=9).

Sequence in context: A271422 A362148 A062374 * A048104 A334801 A362594

Adjacent sequences: A272590 A272591 A272592 * A272594 A272595 A272596

Keyword

nonn

Author

Joerg Arndt, May 05 2016

Status

approved