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A092023
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a(n) is the smallest number m such that m has n distinct prime divisors and if p is a prime divisor of m then p*m - 1 is prime.
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3
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OFFSET
| 1,1
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COMMENTS
| 2004 has this property. i.e. 2004=2^2*3*167, the three numbers 2*2004-1,3*2004-1 and 167*2004-1 are primes. But 2004 is not in the sequence because 2004 is not the smallest number with such property.
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LINKS
| Carlos Rivera, The Prime Puzzles & Problems connection.
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EXAMPLE
| a(7)=55137810 because 55137810=2*3*5*7*13*19*1063 and all the seven numbers 2*55137810-1, 3*55137810-1, 5*55137810-1, 7*55137810-1, 13*55137810-1, 19*55137810-1 and 1063*55137810-1 are prime numbers and 55137810 is the smallest number m with such property.
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CROSSREFS
| Cf. A092024.
Cf. A112723, A112724.
Sequence in context: A054934 A001684 A076926 * A112723 A074777 A007280
Adjacent sequences: A092020 A092021 A092022 * A092024 A092025 A092026
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KEYWORD
| more,nonn
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AUTHOR
| Farideh Firoozbakht (mymontain(AT)yahoo.com), Feb 18 2004
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