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A082716
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Plateau and depression primes of the form (10^a(n)-1)-2*(10^[ a(n)-1 ]+1) or (72*10^[ a(n)-1 ]-27)/9.
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1
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3, 5, 29, 157, 323, 353, 1213, 1285, 7985, 15193, 84773, 119931, 148861
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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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, Prime numbers of the form 799...997.
Index entries for primes involving repunits.
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FORMULA
| a(n) = A056263(n) + 2.
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EXAMPLE
| a(n)=5 -> (10^5-1)-2*(10^4+1) = 79997.
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CROSSREFS
| Cf. A082697-A082720.
Sequence in context: A154942 A092330 A176951 * A060255 A154552 A100857
Adjacent sequences: A082713 A082714 A082715 * A082717 A082718 A082719
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KEYWORD
| nonn
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AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com), Apr 13 2003.
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EXTENSIONS
| a(11)=84773 from Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 03 2011
a(12)=119931 from Ray Chandler (rayjchandler(AT)sbcglobal.net), Apr 01 2011
a(13)=148861 from Ray Chandler (rayjchandler(AT)sbcglobal.net), Apr 09 2011
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