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Search: id:A118370
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| A118370 |
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Divisorial primes: Primes p such that p = prod_{d|n} d + 1 for some n (ordered by n). |
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+0
2
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| 2, 3, 37, 101, 197, 331777, 677, 8503057, 9834497, 5477, 59969537, 8837, 17957, 21317, 562448657, 916636177, 42437, 3208542737, 3782742017, 5006411537, 7676563457, 98597, 106277, 11574317057, 19565295377, 416806419029812551937
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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See A118369 for the corresponding n. These are primes in the sequence 1 + A007955. (The suggested name "divisorial prime" is obviously analogous to that of factorial primes (A088332) and primorial primes (A014545).).
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EXAMPLE
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The prime 37 is a(3) as there exists a number, A118369(3)=6, such that 37 = 6*3*2*1 + 1, where {1,2,3,6} are all the positive divisors of 6.
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PROGRAM
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(PARI) for(n=1, 2500, s=1; fordiv(n, d, s=s*d); if(isprime(s+1), print1(s+1, ", ")))
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CROSSREFS
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Cf. A118369, A007955.
Sequence in context: A118443 A109748 A062459 this_sequence A061576 A144466 A041329
Adjacent sequences: A118367 A118368 A118369 this_sequence A118371 A118372 A118373
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KEYWORD
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nonn
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AUTHOR
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Rick L. Shepherd (rshepherd2(AT)hotmail.com), Apr 25 2006
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