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A082706 Numbers k such that (31*10^(k-1) - 13)/9 is a plateau prime. 1
7, 13, 493, 5569, 24757 (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..5.

Patrick De Geest, PDP Reference Table - 343.

Makoto Kamada, Prime numbers of the form 344...443.

Index entries for primes involving repunits.

FORMULA

a(n) = A056253(n) + 2.

EXAMPLE

k=13 -> (31*10^(13-1) - 13)/9 = 3444444444443.

CROSSREFS

Cf. A082697-A082720, A056253.

Sequence in context: A064119 A224984 A228030 * A201181 A130594 A227173

Adjacent sequences:  A082703 A082704 A082705 * A082707 A082708 A082709

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 January 17 12:18 EST 2020. Contains 330958 sequences. (Running on oeis4.)