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A065997 Numbers n such that sigma(n) / n is prime. 4
6, 28, 120, 496, 672, 8128, 523776, 33550336, 459818240, 1476304896, 8589869056, 14182439040, 31998395520, 51001180160, 137438691328, 518666803200, 13661860101120, 30823866178560, 740344994887680, 796928461056000, 212517062615531520, 2305843008139952128 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This is a subsequence of the sequence of multiply perfect numbers A007691.

The prime values of sigma(n) / n are A219545.

LINKS

Table of n, a(n) for n=1..22.

CROSSREFS

Cf. A007691, A219545.

Sequence in context: A002694 A007691 A260508 * A006516 A171476 A171496

Adjacent sequences:  A065994 A065995 A065996 * A065998 A065999 A066000

KEYWORD

nonn

AUTHOR

Joseph L. Pe, Dec 10 2001

EXTENSIONS

Terms a(10) to a(14) from Jonathan Sondow, Nov 22 2012

Extended by T. D. Noe, Nov 26 2012

STATUS

approved

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Last modified March 24 23:06 EDT 2017. Contains 284035 sequences.