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A102994 Numbers n such that 4*10^n + 6*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 3
1, 2, 7, 9, 14, 24, 45, 49, 73, 74, 232, 338, 397, 504, 1063, 2817, 5305, 16768, 27060 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Also numbers n such that (14*10^n-17)/3 is prime.
a(20) > 10^5. - Robert Price, May 27 2015
LINKS
FORMULA
a(n) = A101729(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(14*10^n - 17)/3], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A074244 A190565 A341631 * A226824 A168132 A211280
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 17 2005
EXTENSIONS
Addition of a(18)-a(19) from Kamada data by Robert Price, Dec 10 2010
STATUS
approved

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Last modified July 17 22:08 EDT 2024. Contains 374377 sequences. (Running on oeis4.)