How to count the 33 days

As we have begun counting the Omer I figured we would spend the next few weeks discussing different Halachos of the Omer. I am willing to bet that you think you know something as true, which in fact has no basis what-so-ever. If you don't believe me- read on and see. Mistaken Fact: The mourning period of Sefira from the 2nd day of Pesach till Lag B'Omer is because Rebbe Akiva's 24,000 talmidim died then. Actual Fact: The Gemara Yevamos (62B) records that all the Talmidim died between Pesach and Shavous. So where do we get our 33 day minhag from? The Medrash has a different opinion on when the deaths occurred and writes that the students of Rebbe Akiva died from Pesach until Pros HaChag (half a month before Shavous). 49 days of Sefira minus half a month (15) gets you 34 days of Aveilus. In fact, the Shulchan Aruch writes (and thus Sefardim are required to follow) that one is not allowed to shave or get married until the 34th day. However we Ashkenazim who say everything is allowed on day 33- what is our basis? The Mahareal writes that really the Gemara Yevamos is right and the 24,000 students did in fact die throughout the whole 49 day period between Pesach and Shavous. However, on days in which Tachanun is not said they did not die. So if you take out a calendar and due some math you have the 7 days remaining of Pesach, 3 days of Rosh Chodesh (2 in Iyar and 1 in Sivan), and 6 Shabbosim in the course of Sefira for a total of 16 days of tachanun freedom. [Editor's note: the fact our shuls don't say tachunun the whole Nissan was a much later invention, and was probably spurred on by the same people that belong to the CNTE: The Committee for No Tachanun Ever: since there must be a bris taking place somewhere in the world] Thus 49 minus 16 equals 33. Of course it's interesting to note that the 33 days we observe were not the actual days they died; we are just observing 33 days to correspond to the 33 that they did in fact die. There are generally 3 ways to observe the 33 days. 1. 2nd day pesach to lag b'omer. 2. 2nd day of Iyar to Erev Shavous. 3. 1st day Rosh Chodesh Iyar (last day in Nissan) till 2nd day of Sivan (1st day of Shloshes Yimey Hagbalah) Rav Moshe writes that since any of the selections above does not correspond to the actual days the students died, one is permitted to switch from his normal custom each year. However, Sefardim who, based on Medrash, hold 34 days, cannot switch there minhag because those are the actual days they died.