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A098919 Least k such that k*M#(n) -1 is prime with M#(n)=product from 1 to n of Mersenne-primes. 0
2, 2, 2, 16, 2, 24, 8, 66, 6, 38, 44, 142, 116, 20, 460, 2974, 5774, 1110, 2520, 3422 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..20.

EXAMPLE

2*(2^2-1)*(2^3-1)*(2^5-1) - 1 = 1301 prime so k(3)=2

CROSSREFS

Sequence in context: A025521 A305109 A068218 * A161748 A195871 A214756

Adjacent sequences:  A098916 A098917 A098918 * A098920 A098921 A098922

KEYWORD

hard,more,nonn

AUTHOR

Pierre CAMI, Oct 17 2004

EXTENSIONS

a(15)-a(20) from Donovan Johnson, Mar 23 2008

STATUS

approved

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Last modified November 15 19:18 EST 2019. Contains 329149 sequences. (Running on oeis4.)