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Search: id:A069179
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| A069179 |
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Least number X such that for each k in (0 to n-1), 2^k*X-1 and 2^k*X+1 are primes. That is, there are N twin primes, each the "double" of the previous. |
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2
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OFFSET
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1,1
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COMMENT
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a(6)=73768891456260 might be called a(6.5), since 64*a(6)+1 is prime. But 64*a(6)-1 is 167*1021*44533*621769, alas.
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EXAMPLE
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a(3) = 211050 because 1*a(3)-1, 1*a(3)+1, 2*a(3)-1, 2*a(3)+1, 4*a(3)-1, and 4*a(3)+1 are all prime.
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CROSSREFS
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Equals A068635 + 1.
Adjacent sequences: A069176 A069177 A069178 this_sequence A069180 A069181 A069182
Sequence in context: A054264 A077305 A133982 this_sequence A058377 A023961 A019976
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KEYWORD
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nonn
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AUTHOR
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Don Reble (djr(AT)nk.ca), Apr 09 2002
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