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 A176994 Least odd prime p such that p#*2^n-1 is prime, with p# the primorial A034386(p). 3
 3, 3, 3, 3, 5, 3, 3, 7, 7, 5, 3, 109, 17, 5, 13, 17, 5, 3, 17, 67, 11, 89, 13, 17, 7, 89, 31, 29, 19, 37, 5, 7, 29, 3, 79, 43, 41, 3, 11, 53, 5, 13, 3, 29, 11, 137, 179, 227, 11, 11, 97, 59, 53, 11, 3, 83, 17, 47, 19, 19, 29, 73, 41, 3, 7, 11, 79, 71, 13, 41, 257, 19, 5, 151, 79, 3, 31, 19, 79, 5, 281, 5, 37, 263, 139, 17, 23, 127, 223, 151, 149, 131, 113, 3, 47, 41, 59, 31, 23, 89 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Pierre CAMI, Table of n, a(n) for n = 0..2642 MATHEMATICA Table[p=3; prod=6; While[! PrimeQ[prod*2^n-1], p=NextPrime[p]; prod=prod*p]; p, {n, 0, 100}] PROG PFGW SCRIPTIFY PROGRAM   Prime P in pfgw.log file   command : pfgw -f in.txt   in.txt file follows SCRIPT DIM nn, -1 DIM kk DIMS tt LABEL loopn SET nn, nn+1 SET kk, 1 LABEL loopk SET kk, kk+1 SETS tt, %d, %d\,; nn; p(kk) PRP p(kk)#*2^nn-1, tt IF !(ISPRP || ISPRIME) THEN GOTO loopk GOTO loopn (Sage) primorial = lambda n: prod(primes(n+1)) # includes n, if prime A176994 = lambda n: next(p for p in Primes() if p > 2 and is_pseudoprime(primorial(p)*2**n-1)) # D. S. McNeil, Dec 09 2010 CROSSREFS Cf. A085427. Sequence in context: A328914 A295084 A068048 * A264050 A262995 A125713 Adjacent sequences:  A176991 A176992 A176993 * A176995 A176996 A176997 KEYWORD nonn AUTHOR Pierre CAMI, Dec 08 2010 STATUS approved

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Last modified September 18 03:09 EDT 2021. Contains 347504 sequences. (Running on oeis4.)