Hi Belg4mit,

Here is my attempt

#!/usr/bin/perl -w

my(@F, @G);
@F = (
      1,
      2,
      4,
      8,
      16,
      32..64,
      17
     );


sub range{
  my($lo, $hi) = @_;

   @G = sort grep {$_ >= $lo and $_ <= $hi} @F;
   return $G[0]..$G[$#G];

}

print join(',', range(25,35)), "\n";
print join(',', range(50,75)), "\n";
print join(',', range(12,35)), "\n";
[download]

this produces

32,33,34,35
50,51,52,53,54,55,56,57,58,59,60,61,62,63,64
16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35
[download]

hope this helps
thinker
Update Changed < to <=
thanks belg4mit
Update2 Read the question properly, and return a range :-)