import datetime days = (len("lundi"), len("mardi"), len("mercredi"), len("jeudi"), len("vendredi"), len("samedi"), len("dimanche")) d = datetime.datetime.strptime("01/01/2000", "%d/%m/%Y") end = datetime.datetime.now() ctr = 0 while True: if (days[d.weekday()] + d.day)%10 == 0: ctr += 1 d = d + datetime.timedelta(days=1) if d > end: break print(d, ctr)