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A154895 Perfect numbers whose number of proper divisors is prime. 0
6, 28, 8128, 137438691328, 2305843008139952128 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..5.

EXAMPLE

28 is member because the number of proper divisors of 28 is 5, a prime number.

CROSSREFS

Cf. A000396, A032741, A133033, A154896.

Sequence in context: A038182 A095723 A057246 * A276493 A074849 A189373

Adjacent sequences:  A154892 A154893 A154894 * A154896 A154897 A154898

KEYWORD

more,nonn

AUTHOR

Omar E. Pol, Jan 25 2009

STATUS

approved

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Last modified October 22 19:53 EDT 2019. Contains 328319 sequences. (Running on oeis4.)