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A103012 Numbers n such that 5*10^n + 3*R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
0, 1, 47, 69, 99, 575, 715, 2179, 10541 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Also numbers n such that (16*10^n+17)/3 is prime.

a(10) > 10^5. - Robert Price, Sep 08 2015

LINKS

Table of n, a(n) for n=1..9.

Makoto Kamada, Prime numbers of the form 533...339.

Index entries for primes involving repunits.

FORMULA

a(n) = A101577(n-1) + 1 for n>1.

EXAMPLE

For n=0, (16*10^n+17)/3=11 which is prime, so 0 is in the sequence.

MATHEMATICA

Do[ If[ PrimeQ[(16*10^n + 17)/3], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101577.

Sequence in context: A245745 A023331 A187923 * A166958 A112056 A033231

Adjacent sequences:  A103009 A103010 A103011 * A103013 A103014 A103015

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Jan 18 2005

EXTENSIONS

a(9) from Kamada data by Robert Price, Dec 14 2010

Inserted a(1)=0 by Robert Price, Sep 08 2015

STATUS

approved

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Last modified December 11 03:15 EST 2016. Contains 279034 sequences.