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A103108 Numbers n such that 9*10^n + 8*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
2, 3, 32, 42, 75, 368, 1392, 16350, 49101, 49689, 91839 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Also numbers n such that (89*10^n-53)/9 is prime.
a(12) > 10^5. - Robert Price, Nov 12 2015
LINKS
FORMULA
a(n) = A101017(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(89*10^n - 53)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A176894 A041053 A212763 * A107124 A141049 A354612
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 19 2005
EXTENSIONS
a(8) from Kamada data by Robert Price, Dec 14 2010
a(9)-a(10) from Erik Branger May 01 2013 by Ray Chandler, Aug 17 2013
a(11) from Robert Price, Nov 12 2015
STATUS
approved

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Last modified March 5 03:04 EST 2024. Contains 370537 sequences. (Running on oeis4.)