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A082710 Plateau and depression primes of the form (10^a(n)-1)/9+6*(10^[ a(n)-1 ]+1) or (64*10^[ a(n)-1 ]+53)/9. 0
10907, 499211 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Prime versus probable prime status and proofs are given in the author's table.

Searched up to n=1200000 by Serge Batalov, Mar 02 2015

REFERENCES

C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.

LINKS

Table of n, a(n) for n=1..2.

Patrick De Geest, PDP Reference Table - 717.

Makoto Kamada, Prime numbers of the form 711...117.

Tanya Khovanova, Non Recursions

C. Rivera and J.C. Rosa, Puzzle 197. Always composite numbers?

EXAMPLE

a(1)=10907 -> (10^10907-1)/9+6*(10^10906+1) = 7111.. ..1117 or 10905 1's surrounded by two 7's.

CROSSREFS

Cf. A082697-A082720.

Sequence in context: A083513 A084277 A259138 * A240604 A065322 A166261

Adjacent sequences:  A082707 A082708 A082709 * A082711 A082712 A082713

KEYWORD

nonn,bref

AUTHOR

Patrick De Geest, Apr 13 2003

EXTENSIONS

Edited by Ray Chandler, Nov 05 2014

Additional PRP term 499211 by Serge Batalov, Mar 01 2015

STATUS

approved

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Last modified September 26 10:46 EDT 2017. Contains 292518 sequences.