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A102979
Numbers n such that 3*10^n + 8*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
0, 1, 6, 10176, 56898
OFFSET
1,3
COMMENTS
Also numbers n such that (35*10^n-17)/9 is prime.
a(6) > 10^5. - Robert Price, Mar 30 2015
FORMULA
a(n) = A101846(n-1) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(35*10^n - 17)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A361901 A329911 A088021 * A069942 A261823 A146202
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Dec 17 2004
EXTENSIONS
Additional term 10176 (a PRP) from Serge Batalov, Oct 12 2008
Addition of a(5) from Kamada data by Robert Price, Dec 13 2010
STATUS
approved