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Matching pairs (Posted on 2015-07-24)

(7,13); (73,137); (41,271);

Both members of each of the above sets share a certain unique feature.

What feature ?

See The Solution Submitted by Ady TZIDON

Rating: 5.0000 (1 votes)

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Solution

Comment 1 of 1

They are the primes p such that 1/p has a certain period.

1/7=0.142857142857...

1/13=0.076923076923...

period=6

1/73=0.0136986301369863...

1/137=0.0072992700729927...

period=8

1/41=0.0243902439...

1/271=0.0036900369...

period=5

Posted by Math Man on 2015-07-24 14:32:07

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