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10001, 100010001, .... (Posted on 2003-05-23) Difficulty: 3 of 5
Consider the following sequence:

10001, 100010001, 1000100010001, 10001000100010001, 100010001000100010001,....

Show that none of them are prime numbers.

See The Solution Submitted by Fernando    
Rating: 3.3333 (6 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
First observations | Comment 2 of 12 |
If the number of ones in a member of the sequence is composite, then the member itself is composite.

Example: 100010001000100010001 has 6 ones and is composite (100010001)*(1000000000001)
  Posted by Brian Smith on 2003-05-23 14:21:20
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