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A135725 Positive integers n such that n!!!-1 = A007661(n)-1 is prime. +0
2
3, 4, 6, 8, 20, 26, 36, 50, 60, 114, 135, 138, 248, 315, 351, 429, 642 (list; graph; listen)
OFFSET

1,1

LINKS

Ken Davis, Status of Search for Multifactorial Primes

ProthSearch.net (on web.archive.org), n3minus.txt

EXAMPLE

a(4)=8 since 8!!!-1 = 8x5x2-1 = 79 is the 4th prime of that form.

PROGRAM

(PARI) A007661(n) = prod(i=1, (n-1)\3, n-=3, n+!n) /* newline */ for(n=1, 999, if(isprime(A007661(n)-1), print1(n", ")))

CROSSREFS

Cf. A007661, A135726, A037082, A037083.

Sequence in context: A007749 A139452 A063506 this_sequence A084438 A080710 A115837

Adjacent sequences: A135722 A135723 A135724 this_sequence A135726 A135727 A135728

KEYWORD

hard,more,nonn

AUTHOR

M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Nov 26 2007

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Last modified July 23 10:48 EDT 2008. Contains 142285 sequences.


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