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A103086
Numbers n such that 8*10^n + 5*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
1, 2, 8, 17, 19, 25, 40, 49, 58, 59, 92, 113, 296, 637, 1856, 2515, 3593, 6991, 11840, 86072, 93508
OFFSET
1,2
COMMENTS
Also numbers n such that (77*10^n+31)/9 is prime.
a(22) > 10^5. - Robert Price, Oct 26 2015
FORMULA
a(n) = A101073(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(77*10^n + 31)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A009662 A279243 A162218 * A192155 A131362 A370854
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 19 2005
EXTENSIONS
a(19) from Kamada data by Robert Price, Dec 14 2010
a(20)-a(21) from Robert Price, Oct 26 2015
STATUS
approved