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A137906
Least k such that k*(2^p-1)*(k*(2^p-1)-1)-1 is prime, where 2^p-1 runs through the Mersenne primes.
3
1, 1, 1, 1, 1, 4, 1, 27, 14, 34, 6, 132, 97, 1, 500, 1816, 1292, 136, 2445, 15, 1934, 5472, 1584, 2734, 21022, 5870
OFFSET
1,6
EXAMPLE
1*(2^2-1)*(1*(2^2-1)-1)-1=5 prime, 2^2-1 first Mersenne prime, a(1)=1;
1*(2^3-1)*(1*(2^3-1)-1)-1=41 prime, 2^3-1 second Mersenne prime, a(2)=1.
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Pierre CAMI, Feb 22 2008
STATUS
approved