use proconio::input;

fn main() {
    input! {
        n: usize,
        a: [usize; n],
    }

    let mut values = a.clone();
    values.sort();
    values.dedup();

    let mut counts = vec![0; values.len()];
    for x in &a {
        let i = values.binary_search(&x).unwrap();
        counts[i] += 1;
    }

    let mut prefix_counts = vec![0; values.len() + 1];
    for i in 0 .. values.len() {
        prefix_counts[i + 1] += prefix_counts[i] + counts[i];
    }

    let mut ans = 0_usize;
    for i in 0 .. values.len() {
        if counts[i] >= 2 {
            let x = values[i];
            let j = values.partition_point(|&y| y < x * 2 );
            ans += counts[i] * (counts[i] - 1) / 2 * (prefix_counts[j] - counts[i]);
        }
    }

    println!("{ans}");
}