#!/usr/bin/perl
use strict;
use warnings;
use Date::Manip;
use feature 'say';

my ($start, $end) = qw(2017-01-01 2017-12-31);

# y:m:w:d:h:m:s
my @days = ParseRecur('0:0:0:1:0:0:0', $start, $start, $end);
my @weeks = ParseRecur('0:0:1::0:0:0', $start, $start, $end);
my @months = ParseRecur('0:1:0::0:0:0', $start, $start, $end);
my @years = ParseRecur('1:0:0::0:0:0', $start, $start, $end);
my @datesEvery15th = ParseRecur('0:0:0:15:0:0:0', $start, $start, $end);

say "Number of days: " . scalar @days;
say "Number of weeks: " . scalar @weeks;
say "Number of months: " . scalar @months;
say "Number of years: " . scalar @years;
say "Number of payments: " . scalar @datesEvery15th;

=print payment dates
for my $date (@dates15th) {
    say UnixDate($date, "%Y-%m-%d");
}
=cut

__END__

$ perl test.pl
Number of days: 365
Number of weeks: 53
Number of months: 12
Number of years: 1
Number of payments: 25