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A103029
Numbers n such that 6*10^n + R_n + 8 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
2, 260, 417, 953, 2138, 2969, 3045, 11777, 23648
OFFSET
1,1
COMMENTS
Also numbers n such that (55*10^n+71)/9 is prime.
a(10) > 10^5. - Robert Price, Sep 08 2015
FORMULA
a(n) = A101521(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(55*10^n + 71)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A218435 A089663 A252708 * A122862 A236437 A137105
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 18 2005
EXTENSIONS
Addition of a(8)-a(9) from Kamada data by Robert Price, Dec 13 2010
STATUS
approved