Proper divisors

Arturo

<lang rebol>properDivisors: function [x] ->

   (factors x) -- x

loop 1..10 'x ->

   print ["proper divisors of" x "=>" properDivisors x]

maxN: 0 maxProperDivisors: 0

loop 1..20000 'x [

   pd: size properDivisors x
   if maxProperDivisors < pd [
       maxN: x
       maxProperDivisors: pd
   ]

]

print ["The number with the most proper divisors (" maxProperDivisors ") is" maxN]</lang>

Output:

proper divisors of 1 => [] 
proper divisors of 2 => [] 
proper divisors of 3 => [1] 
proper divisors of 4 => [1 2] 
proper divisors of 5 => [1] 
proper divisors of 6 => [1 2 3] 
proper divisors of 7 => [1] 
proper divisors of 8 => [1 2 4] 
proper divisors of 9 => [1 3] 
proper divisors of 10 => [1 2 5] 
The number with the most proper divisors ( 79 ) is 15120