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A068412
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Composite n such that phi(n) divides sigma(n)-2*n.
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0
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6, 12, 28, 42, 60, 168, 456, 496, 828, 1080, 1242, 1530, 1560, 3360, 3672, 4560, 7320, 7584, 8128, 11400, 14784, 19488, 21648, 33462, 37536, 40608, 44856, 48024, 59520, 83904, 87648, 221088, 352704, 354384, 560664, 613440, 1288224, 1365984, 1420320, 1482480
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The first four numbers in this sequence {6, 12, 28, 42} are featured in the cult film "Donnie Darko", in which the title character is warned that the world will end in 28 days, 6 hours, 42 minutes and 12 seconds. - Don Rogers (donrogers42(AT)aol.com), Sep 21 2006
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PROG
| PARI : for(n=2, 300000, if((sigma(n)-2*n)%(eulerphi(n))==isprime(n), print1(n, ", ")))
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CROSSREFS
| Sequence in context: A064987 A185152 A057341 * A183026 A146005 A109510
Adjacent sequences: A068409 A068410 A068411 * A068413 A068414 A068415
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KEYWORD
| easy,nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Mar 03 2002
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EXTENSIONS
| More terms from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Apr 08 2002
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