Function catalan_number 

pub fn catalan_number(n: u64) -> u128

n-th Catalan number: C(n) = (1/(n+1)) * C(2n, n).

Examples

use mathverse_core::integer::catalan_number;

assert_eq!(catalan_number(0), 1);
assert_eq!(catalan_number(3), 5);
assert_eq!(catalan_number(5), 42);