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A272592 Numbers n such that the multiplicative group modulo n is the direct product of 2 cyclic groups. 1
8, 12, 15, 16, 20, 21, 28, 30, 32, 33, 35, 36, 39, 42, 44, 45, 51, 52, 55, 57, 63, 64, 65, 66, 68, 69, 70, 75, 76, 77, 78, 85, 87, 90, 91, 92, 93, 95, 99, 100, 102, 108, 110, 111, 114, 115, 116, 117, 119, 123, 124, 126, 128, 129, 130, 133, 135, 138, 141, 143, 145, 147, 148, 150, 153, 154, 155, 159, 161 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers n such that A046072(n) = 2.

LINKS

Table of n, a(n) for n=1..69.

PROG

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

CROSSREFS

Direct product of k groups: A033948 (k=1), A272593 (k=3), A272594 (k=4), A272595 (k=5), A272596 (k=6), A272597 (k=7), A272598 (k=8), A272599 (k=9).

Sequence in context: A050275 A033949 A175594 * A062373 A180690 A194592

Adjacent sequences:  A272589 A272590 A272591 * A272593 A272594 A272595

KEYWORD

nonn

AUTHOR

Joerg Arndt, May 03 2016

STATUS

approved

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Last modified April 22 04:04 EDT 2019. Contains 322329 sequences. (Running on oeis4.)