Because none of them would be able to endorse me. I have checked their names on the ArXive, and it appears that none of them have submitted anything at all (they usually get their articles published in journals and similar).
I am an italian undergraduate maths student. I have recently written two brief mathematical papers on prime numbers. In the first one, I have proved a simple method to solve the factoring problem (that is, given the product p of two primes a and b, find a and b). In the second one, I have...