If one removes the repetitive letters, then the number of letters mentioned at the beginning of the Surahs is fourteen: Alif, Lam, Mim, Sad, Ra, Kaf, Ha, Ya, `Ayn, Ta, Sin, Ha, Qaf, Nun.
So glorious is He Who made everything subtly reflect His wisdom.
Moreover, the scholars said, "There is no doubt that Allah did not reveal these letters for jest and play.'' Some ignorant people said that some of the Qur'an does not mean anything, (meaning, such as these letters) thus committing a major mistake. On the contrary, these letters carry a specific meaning. Further, if we find an authentic narration leading to the Prophet that explains these letters, we will embrace the Prophet's statement. Otherwise, we will stop where we were made to stop and will proclaim,
﴿ءَامَنَّا بِهِ كُلٌّ مِّنْ عِندِ رَبِّنَا﴾
(We believe in it; all of it (clear and unclear verses) is from our Lord) (3:7).
The scholars did not agree on one opinion or explanation regarding this subject. Therefore, whoever thinks that one scholar's opinion is correct, he is obliged to follow it, otherwise it is better to refrain from making any judgment on this matter. Allah knows best.