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A103095
Numbers n such that 9*10^n + 2*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
1
1, 3, 4, 15, 153, 322, 471, 561, 664, 2157, 3697, 14875, 19270, 22095
OFFSET
1,2
COMMENTS
Also numbers n such that (83*10^n+43)/9 is prime.
a(15) > 10^5. - Robert Price, Nov 02 2015
FORMULA
a(n) = A101003(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(83*10^n + 43)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A115752 A346974 A354395 * A041325 A042541 A325212
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 19 2005
EXTENSIONS
a(12)-a(14) from Kamada data by Robert Price, Dec 14 2010
STATUS
approved