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A068489
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m for which p(m) is the least prime dividing #p(n) - 1, i.e. one less than primorial n-th prime (A057588).
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1
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3, 10, 5, 343, 3248, 18, 16, 12, 22, 20324, 50, 9414916809095, 13120, 43, 8481, 1200361259, 196, 38, 10326732314, 65, 38, 34
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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COMMENTS
| Since #P13 -1 is a prime, see A006794, we need the number of primes less than or equal to #P13 -1. The sequence continues 13120,43,8481,1200361259,196,38,10326732314,65,38,34,
a(24) = pi(23768741896345550770650537601358309). [From Donovan Johnson (donovan.johnson(AT)yahoo.com), Dec 08 2009]
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LINKS
| Hisanori Mishima, Factorization results #Pn (Primorial) - 1
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FORMULA
| PrimePi(A057713)
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MATHEMATICA
| Do[ Print[ PrimePi[ FactorInteger[ Product[ Prime[k], {k, 1, n}] - 1] [[1, 1]]]], {n, 2, 22} ]
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CROSSREFS
| Cf. A068488.
Sequence in context: A033478 A111127 A140948 * A088337 A195919 A087397
Adjacent sequences: A068486 A068487 A068488 * A068490 A068491 A068492
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KEYWORD
| hard,more,nonn
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AUTHOR
| Lekraj Beedassy (blekraj(AT)yahoo.com), Mar 11 2002
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EXTENSIONS
| Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 12 2002
a(13) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Dec 08 2009
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