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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.

  Submitted by Math Man    
Rating: 5.0000 (1 votes)
Solution: (Hide)
6, 60, 90, 87360

Comments: ( You must be logged in to post comments.)
  Subject Author Date
Hints/Tipsre(4): just look up by SHAdy TZIDON2013-12-17 10:16:06
re(3): just ...correctionCharlie2013-12-17 10:07:19
re(3): just look up by SHCharlie2013-12-17 10:04:18
Some Thoughtsre(2): just look up by SHAdy TZIDON2013-12-17 04:25:33
Hints/Tipsre(2): just ...correctionAdy TZIDON2013-12-17 02:58:28
Some Thoughtsre: just look up - spoilerSteve Herman2013-12-16 19:37:23
That was quick!Math Man2013-12-16 19:24:14
re: just look up - spoilerCharlie2013-12-16 16:41:29
Solutioncomputer solutionCharlie2013-12-16 16:26:07
Solutionjust look up - spoilerAdy TZIDON2013-12-16 14:52:26
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