Once again we use day 0-6. I have added a hash to show the output in a nice format. Oh you can do it in a one liner as shown :-). The advantage of 0-6 for the days is that we can use modulus to good effect to generate our 7 indexes (0-6) for the days. You could always copy element 0 of the day count array to element 7 if you are really set on having Sunday as day 7 or add 1 to the mod and iterate from ($firstday-1)..($days+$firstday-2) but you do waste element 0 in your array.

my $days = 71;
my $firstday = 5;
my @daycounts = (0) x 7; # initialise 7 array elements to 0

for my $day_num( $firstday .. ($days+$firstday-1) ) {
    $daycounts[$day_num%7]++;
}

# now print it out nice and pretty

my %weekdays = (
    1 => Monday,
    2 => Tuesday,
    3 => Wednesday,
    4 => Thursday,
    5 => Friday,
    6 => Saturday,
    0 => Sunday);

for my $day_num(0..6) {
    print "$daycounts[$day_num]\t$weekdays{$day_num}\n";
}

# here it is as a one liner
$daycounts[$_%7]++ for $firstday..($days+$firstday-1);
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tachyon

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