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URL: https://oeis.org/A102936

⇱ A102936 - OEIS

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A102936
Numbers k such that 10^k + 5*R_k - 2 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
1
1, 3, 6, 15, 70, 76, 13024, 60346
OFFSET
1,2
COMMENTS
Also numbers k such that (14*10^k - 23)/9 is prime.
a(9) > 10^5. - Robert Price, Apr 10 2015
FORMULA
a(n) = A102019(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(14*10^n - 23)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A241269 A102356 A208662 * A009192 A013273 A013277
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Dec 16 2004
EXTENSIONS
Addition of a(7) from Kamada data by Robert Price, Dec 13 2010
a(8) from Robert Price, Apr 10 2015
STATUS
approved