Solve challenges in Rust

palindrome_numeric.rs

/// Found palindrome numeric
fn is_palindrome_numeric(n: String) -> bool {
    n == n.chars().rev().collect::<String>()
}

fn main() {
    for i in 1..20 {
        if is_palindrome_numeric(format!("{}", i)) {
            println!("{}", i)
        }
    }
}

prime.rs

/// Solve prime number with Sieve of Eratosthenes
fn sieve(list: &[i64]) {
    if let Some((head, tail)) = list.split_first() {
        let ys: Vec<i64> = tail.iter().filter(|n| *n % head != 0).cloned().collect();
        print!("{}, ", head);
        sieve(&ys[..]);
    }
}

fn main() {
    let numbers: Vec<i64> = (2..10_000).map(|n| n).collect();
    sieve(&numbers[..]);
}