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A082699
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Plateau and depression primes of the form 5*(10^a(n)-1)/9-4*(10^[ a(n)-1 ]+1) or (14*10^[ a(n)-1 ]-41)/9.
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1
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OFFSET
| 0,1
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COMMENTS
| Prime versus probable prime status and proofs are given in the author's table.
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REFERENCES
| C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
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LINKS
| P. De Geest, PDP Reference Table
Makoto Kamada, Factorizations of 155...551.
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EXAMPLE
| a(n)=21 -> 5*(10^21-1)/9-4*(10^20+1) = 155555555555555555551.
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CROSSREFS
| Cf. A082697 up to A082720.
Sequence in context: A128561 A032414 A062225 * A096729 A001775 A148548
Adjacent sequences: A082696 A082697 A082698 * A082700 A082701 A082702
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KEYWORD
| nonn,base
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AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com), Apr 13 2003.
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EXTENSIONS
| 37685 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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