Largest proper divisor of n

1..100 -> map {|n| proper_divisors(n).tail \\ 1 }.slices(10).each {|a|
    a.map{ '%3s' % _ }.join(' ').say
}

Output:

  1   1   1   2   1   3   1   4   3   5
  1   6   1   7   5   8   1   9   1  10
  7  11   1  12   5  13   9  14   1  15
  1  16  11  17   7  18   1  19  13  20
  1  21   1  22  15  23   1  24   7  25
 17  26   1  27  11  28  19  29   1  30
  1  31  21  32  13  33   1  34  23  35
  1  36   1  37  25  38  11  39   1  40
 27  41   1  42  17  43  29  44   1  45
 13  46  31  47  19  48   1  49  33  50