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URL: https://oeis.org/A103012

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A103012
Numbers k such that 5*10^k + 3*R_k + 6 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
1
0, 1, 47, 69, 99, 575, 715, 2179, 10541
OFFSET
1,3
COMMENTS
Also numbers k such that (16*10^k+17)/3 is prime.
a(10) > 10^5. - Robert Price, Sep 08 2015
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
Sequence in context: A245745 A023331 A187923 * A166958 A112056 A033231
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