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A063785
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Numbers n such that sigma(n) = 2n + omega(n), where omega(n) is the number of distinct prime divisors of n.
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0
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20, 104, 464, 1952, 4030, 5830, 130304, 522752, 1848964, 8382464, 134193152
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| It is easily proved that if 2^m-3 is prime then 2^(m-1)*(2^m-3) is in the sequence. - Farideh Firoozbakht (mymontain(AT)yahoo.com), Feb 12 2008
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PROG
| (PARI) for(n=1, 10^8, if(sigma(n)==2*n+omega(n), print(n)))
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CROSSREFS
| Cf. A045768.
Sequence in context: A189950 A045768 A088831 * A181703 A135174 A173963
Adjacent sequences: A063782 A063783 A063784 * A063786 A063787 A063788
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KEYWORD
| nonn
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AUTHOR
| Jason Earls (zevi_35711(AT)yahoo.com), Aug 17 2001
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