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Repunits and bases (
Posted on 20130724
)
11
_{2}
=3 and 111
_{3}
=13 are prime. However, 1111
_{4}
=85=5*17 and 11111
_{5}
=781=11*71 are not prime. What is the least number n>3 such that the repunit consisting of n 1's in base n is prime?
Submitted by
Math Man
No Rating
Solution:
(
Hide
)
19 since 1111111111111111111
_{19}
=109912203092239643840221 is prime.
Comments: (
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Subject
Author
Date
re(3): Answer: for any composite, odd or even
Steve Herman
20130725 09:31:14
re(2): Answer: for any composite, odd or even
Ady TZIDON
20130724 15:36:40
re(2): Answer:
Steve Herman
20130724 12:53:15
re: Answer:
Charlie
20130724 12:42:29
computer solution
Charlie
20130724 12:40:09
Answer:
broll
20130724 11:29:46
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