Prime Friday calculator

prime-friday.py

from datetime import date, timedelta

# This is a static set of all prime Month and plus Day (2 digits) integers. Since it's static we retain this set
# for all comparisons rather than compute it every time.
def isPrime(candidate):
    primeSet = [101,103,107,109,113,127,131,211,223,227,229,307,311,313,317,331,401,409,419,421,
        503,509,521,523,601,607,613,617,619,701,709,719,727,733,809,811,821,823,827,829,907,911,919,929,
        1009,1013,1019,1021,1031,1103,1109,1117,1123,1129,1201,1213,1217,1223,1229,1231]

    return candidate in primeSet 

today = date.today()
week = timedelta(weeks=1)

# Determine the next Friday.
fridayDiff = 4 - date.weekday(today)

if fridayDiff >= 0:
    # If it's Friday or earlier in the week just add the days
    nextFriday = today + timedelta(days = fridayDiff)
else:
    # If we are past Friday then move a week ahead and back up to Friday.
    nextFriday = today + timedelta(days = 7 + fridayDiff)

# Find a year's worth of Fridays
for i in range(1,52):
    
    n = nextFriday + (week * i)

    # Cast the combination of ordinal month with 2 digit day as an integer
    dateInt = int(n.month.__str__() + n.strftime('%d'))
    
    # If the date is "prime" print it
    if isPrime(dateInt):
        print(n.ctime())