perl -e 'for my $i (1 .. (2<<4)-1){(1&($i>>$_)) && print 1+$_," " for 0..4; print"\n"} '
1 
2 
1 2 
3 
1 3 
2 3 
1 2 3 
4 
1 4 
2 4 
1 2 4 
3 4 
1 3 4 
2 3 4 
1 2 3 4 
5 
1 5 
2 5 
1 2 5 
3 5 
1 3 5 
2 3 5 
1 2 3 5 
4 5 
1 4 5 
2 4 5 
1 2 4 5 
3 4 5 
1 3 4 5 
2 3 4 5 
1 2 3 4 5