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Search: id:A081618
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| A081618 |
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Numbers n such that (product of first n primes)+1 is divisible by the (n+1)-th prime. Also n such that A075306(n)-1 is equal to A002110(n). Positions of 1 in A081617. |
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+0
2
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OFFSET
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1,2
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COMMENT
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a(5) is greater than 10^5.
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EXAMPLE
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The 8th prime, 19, divides 2*3*5*7*11*13*17+1=510511, thus 7 is a member.
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PROGRAM
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(PARI) p=1:for(n=1, 10^5, p=p*prime(n):if((p+1)%prime(n+1)==0, print1(n", ")))
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CROSSREFS
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Adjacent sequences: A081615 A081616 A081617 this_sequence A081619 A081620 A081621
Sequence in context: A015506 A123832 A093167 this_sequence A120661 A139057 A086214
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KEYWORD
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nonn,hard,more
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AUTHOR
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Ralf Stephan (ralf(AT)ark.in-berlin.de), Mar 24 2003
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