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A079324 k such that 2kp+1 is the first factor of a nonprime Mersenne number M(p) = 2^p - 1. 1
1, 1, 4, 3, 163, 5, 25, 60, 1525, 1445580, 1609, 3, 17, 1, 59, 36793758459 (list; graph; refs; listen; history; internal format)
OFFSET

0,3

EXAMPLE

2^11-1=23.89, 23=2.1.11+1, therefore a(1)=1.

PROG

(PARI) forprime (n=3, 101, v=2^n-1; if (!isprime(v), print1((factor(v)[, 1][1]-1)\(2*n)", ")))

CROSSREFS

Cf. A054723.

Sequence in context: A025175 A016504 A013335 * A002298 A195565 A197243

Adjacent sequences:  A079321 A079322 A079323 * A079325 A079326 A079327

KEYWORD

nonn

AUTHOR

Jon Perry (perry(AT)globalnet.co.uk), Feb 12 2003

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Last modified February 14 11:36 EST 2012. Contains 205623 sequences.