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Search: id:A139426
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| A139426 |
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Smallest number k such that M(n)^2+k*M(n)-1 is prime with M(n)= Mersenne primes =A000668(n). |
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+0
8
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| 1, 5, 1, 5, 11, 11, 17, 19, 23, 97, 127, 145, 167, 269, 767, 479, 3307, 1453, 18007, 2357, 599, 17669, 5527, 3191, 3251
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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All primes certified using openpfgw_v12 from primeform group
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EXAMPLE
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3*3+1*3-1=11 prime 3=M(1)=2^2-1 so k(1)=1
7*7+5*7-1=83 prime 7=M(2)=2^3-1 so k(2)=5
31*31+1*31-1=991 prime 31=M(3)=2^5-1 so k(3)=1
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CROSSREFS
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Cf. A000668, A139424, A139425, A139427, A139428, A139429, A139430, A139421.
Adjacent sequences: A139423 A139424 A139425 this_sequence A139427 A139428 A139429
Sequence in context: A103986 A128359 A131113 this_sequence A143384 A046611 A101692
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KEYWORD
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hard,more,nonn
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AUTHOR
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Pierre CAMI (pierrecami(AT)tele2.fr), Apr 21 2008
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