Finding the first few hundred thousand primes is a trivial problem as many of the answers here show. If you are looking for a challenge with prime numbers try one of these:

- write a program that finds the N-th prime number, where N is supplied by the user when invoking the procedure. For example
`(nth-prime 5)`

would return 11 since 11 is the fifth prime (assuming primes start at 2). The user will test this function by passing values greater than 10000000 (ten million) to`nth-prime`

. - write a program that finds the first prime number (not a pseudo prime number) after a value X, where X is supplied by the user when invoking the procedure. For example
`(first-prime-after 5)`

would return 7, since 7 is the first prime greater than 5. The user will test this function by passing values greater than 18446744073709551616 to`first-prime-after`

(i.e values larger than 64 bits).

Enjoy,

Alex.