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A103006 Numbers n such that 5*10^n + R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
0, 23, 53, 12809, 15071 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Also numbers n such that (46*10^n+53)/9 is prime.
a(6) > 10^5. - Robert Price, Jun 20 2015
LINKS
FORMULA
a(n) = A101571(n-1) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(46*10^n + 53)/9], Print[n]], {n, 0, 10000}]
Select[Range[0, 15100], PrimeQ[FromDigits[Join[PadRight[{5}, #, 1], {7}]]]&] (* Harvey P. Dale, Mar 13 2012 *)
CROSSREFS
Sequence in context: A238854 A045345 A133986 * A053236 A118603 A303891
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 18 2005
EXTENSIONS
One more PRP term from Serge Batalov, Oct 13 2008
Addition of a(5) from Kamada data by Robert Price, Dec 13 2010
STATUS
approved

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Last modified March 19 01:34 EDT 2024. Contains 370952 sequences. (Running on oeis4.)