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A082705 Numbers k such that (29*10^(k-1) + 7)/9 is a depression prime. 1
7, 9, 895, 1525, 3037, 21157 (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.

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..6.

Patrick De Geest, PDP Reference Table - 323.

Makoto Kamada, Prime numbers of the form 322...223.

Index entries for primes involving repunits.

FORMULA

a(n) = A056252(n) + 2.

EXAMPLE

k=9 -> (29*10^(9-1) + 7)/9 = 322222223.

CROSSREFS

Cf. A082697-A082720, A056252.

Sequence in context: A306184 A027723 A046265 * A122577 A180732 A266551

Adjacent sequences:  A082702 A082703 A082704 * A082706 A082707 A082708

KEYWORD

nonn,base,hard,more

AUTHOR

Patrick De Geest, Apr 13 2003

EXTENSIONS

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

Edited by Ray Chandler, Nov 05 2014

STATUS

approved

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Last modified February 16 21:37 EST 2020. Contains 331975 sequences. (Running on oeis4.)