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A128276
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a(n) is the least product of n odd primes m=p1*p2*...*pn, such that for all divisor d|2*m, d+2*m/d is prime.
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5
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OFFSET
| 1,1
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COMMENTS
| 1. a(5) > 2*10^9 2. (C. Pomerance) The prime k-tuple conjecture implies a(n) exists for all n
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EXAMPLE
| 105=3*5*7 and 2*3*5*7+1, 3*5*7+2, 2*5*7+3, 2*3*7+5, 2*3*5+7, 2*3+5*7, 2*5+3*7, 2*7+3*5 are all primes and 105 is the smallest such integer which is the product of 3 odd primes, so a(3)=105
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CROSSREFS
| Sequence in context: A048599 A129731 A088109 * A107878 A120016 A074519
Adjacent sequences: A128273 A128274 A128275 * A128277 A128278 A128279
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KEYWORD
| hard,more,nonn
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AUTHOR
| Kok Seng Chua (chuakokseng(AT)hotmail.com), Feb 23 2007
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EXTENSIONS
| Typo in a(4) corrected by T. D. Noe (noe(AT)sspectra.com), Aug 04 2010
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