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A103085 Numbers n such that 8*10^n + 5*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
2, 8, 1056, 19835, 20018, 36464, 81606 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Also numbers n such that (77*10^n+13)/9 is prime.
a(8) > 10^5. - Robert Price, Oct 25 2015
LINKS
FORMULA
a(n) = A101072(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(77*10^n + 13)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A132573 A322142 A061591 * A084148 A014115 A014116
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 19 2005
EXTENSIONS
a(4)-a(6) from Kamada data by Robert Price, Dec 14 2010
a(7) from Robert Price, Oct 25 2015
STATUS
approved

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Last modified March 28 04:05 EDT 2024. Contains 371235 sequences. (Running on oeis4.)