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Search: id:A082718
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| A082718 |
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Plateau and depression primes of the form 2*(10^a(n)-1)/9+7*(10^[ a(n)-1 ]+1) or (83*10^[ a(n)-1 ]+61)/9. |
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+0
2
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OFFSET
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0,1
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COMMENT
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Prime versus probable prime status and proofs are given in the author's table.
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REFERENCES
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C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
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LINKS
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P. De Geest, PDP Reference Table
Makoto Kamada, Factorizations of 922...229.
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EXAMPLE
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a(n)=13 -> 2*(10^13-1)/9+7*(10^12+1) = 9222222222229.
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CROSSREFS
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Cf. A082697 up to A082720.
Equals A056265 + 2.
Sequence in context: A137474 A071087 A038691 this_sequence A154821 A084741 A135623
Adjacent sequences: A082715 A082716 A082717 this_sequence A082719 A082720 A082721
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KEYWORD
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nonn,base
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AUTHOR
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Patrick De Geest (pdg(AT)worldofnumbers.com), Apr 13 2003.
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EXTENSIONS
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37787 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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