chip@chip:~/watchmaking$ cat holes.pl
#!/usr/bin/perl
use POSIX;
open(FP, "<holes");
while($hole = <FP>)
{
        chomp $hole;
        print "$hole:\n";
        for($i=2; $i<$hole; $i++) {
                print "\t$i\n" if isdigit ($hole/$i); }
}
chip@chip:~/watchmaking$ ./holes.pl > holes_able
Calling POSIX::isdigit() is deprecated at ./holes.pl line 8, <FP> line 1.
chip@chip:~/watchmaking$ cat holes_able
51:
        3
        17
53:
55:
        5
        11
57:
        3
        19
59:
63:
        3
        7
        9
        21
65:
        5
        13
67:
69:
        3
        23
71:
75:
        3
        5
        15
        25
77:
        7
        11
79:
82:
        2
        41
86:
        2
        43
92:
        2
        4
        23
        46
96:
        2
        3
        4
        6
        8
        12
        16
        24
        32
        48
100:
        2
        4
        5
        10
        20
        25
        50
360:
        2
        3
        4
        5
        6
        8
        9
        10
        12
        15
        18
        20
        24
        30
        36
        40
        45
        60
        72
        90
        120
        180
366:
        2
        3
        6
        61
        122
        183
chip@chip:~/watchmaking$