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Search: id:A098917
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| A098917 |
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Least k such that k*Mersenne-prime(n)*Mersenne-prime(n+1) + 1 is prime. |
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+0
1
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| 2, 6, 4, 16, 36, 6, 42, 24, 172, 18, 52, 54, 6, 130
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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2*(2^2-1)*(2^3-1) + 1 = 43 prime so k(1)=2
2*(2^3-1)*(2^5-1) + 1 = 435 composite
4*(2^3-1)*(2^5-1) + 1 = 867 composite
6*(2^3-1)*(2^5-1) + 1 = 1303 prime so k(2)=6
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CROSSREFS
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Adjacent sequences: A098914 A098915 A098916 this_sequence A098918 A098919 A098920
Sequence in context: A110346 A095754 A127320 this_sequence A054786 A033457 A133936
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KEYWORD
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nonn
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AUTHOR
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Pierre CAMI (pierrecami(AT)tele2.fr), Oct 17 2004
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