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Unitary perfect numbers (Posted on 2013-12-16) Difficulty: 3 of 5
A unitary divisor of a number n is a number d such that d|n and gcd(d, n/d)=1. For example, 3 is a unitary divisor of 12 because gcd(3, 12/3)=gcd(3, 4)=1.

A unitary perfect number is a number that is the sum of its unitary divisors less than itself. For example, 60 is a unitary perfect number because its unitary divisors less than itself are 1, 3, 4, 5, 12, 15, and 20, and 1+3+4+5+12+15+20=60. Find all unitary perfect numbers less than 1000000.

See The Solution Submitted by Math Man    
Rating: 5.0000 (1 votes)

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Hints/Tips re(2): just ...correction | Comment 6 of 10 |
(In reply to re: just look up - spoiler by Charlie)

The 5th UP number decomposes into 2^18*3*...313, not 2^17*...

The  quantity 4095, clearly, stays unchanged.

  Posted by Ady TZIDON on 2013-12-17 02:58:28
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