Function primecount::phi

pub fn phi(x: i64, a: i64) -> i64

Partial sieve function (a.k.a. Legendre-sum).

phi(x, a) counts the numbers <= x that are not divisible by any of the first a primes.

Returns -1 if an error occurs.

Examples

// The numbers are: 1, 5 and 7.
assert_eq!(primecount::phi(10, 2), 3);

// The numbers are: 1, 7, 11 and 13.
assert_eq!(primecount::phi(15, 3), 4);

assert_eq!(primecount::phi(10i64.pow(12), 78498i64), 37607833521)