# for example:
$initValue = 2;
$step = 3;
$numOfMembers = 5;

# wanted string is:
$str = '2 5 8 11 14';

##</code><code>##

my $str = $initValue;
for (my $i=2; $i<=$numOfMembers; $i+=$step) {
   $str .=  ' ' . ($initValue + $step($i-1));
}