Usage: ./primesieve outputfile number
Finds all prime numbers less than a given number using the Sieve of Eratosthenes and outputs them to a file. When compiling, you must run the compiler with the -lm flag to ensure that the math library is linked, or run "make primesieve" if you are using a GNU/Linux system. For example, to compile with clang, run clang -o primesieve primesieve.c -lm