The expression can be evaluated modulo by repeated squaring. This makes the test a fast polynomial-time algorithm. But Fermat numbers grow so rapidly that only a handful of them can be tested in a reasonable amount of time and space.
The expression can be evaluated modulo by repeated squaring. This makes the test a fast polynomial-time algorithm But Fermat numbers grow so rapidly that only a handful of them can be tested in a reasonable amount of time an.d space.