map{
   $m=!s/$/, /;
   $x=y/,//;
   for$n(1..$x){/^((?:\d+, ){$n})\1+$/&&{$m=$n,last}}
   print$/,($m>0?$x/$m:0);
}<DATA>
__DATA__
1, 2, 5, 1, 2, 5, 1, 2, 5
3, 6, 3, 6, 3, 6, 3, 6
4, 1, 28, 0, 4, 1, 28, 0
3, 5, 17, 3, 17, 5
4, 1, 28, 0, 4, 1, 28