package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func power(base, exp int) int {
	res := 1
	base %= 998244353
	for exp > 0 {
		if exp%2 == 1 {
			res = (res * base) % 998244353
		}
		base = (base * base) % 998244353
		exp /= 2
	}
	return res
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)

	if !scanner.Scan() {
		return
	}
	m, _ := strconv.Atoi(scanner.Text())

	const P = 998244353
	const P_1 = 998244352
	const MAXA = 100005

	cnt := make([]bool, MAXA)
	cnt_exp := make([]int, MAXA)
	cnt_mod := make([]int, MAXA)
	sum1 := make([]int, MAXA)
	sum2 := make([]int, MAXA)

	for i := 0; i < m; i++ {
		scanner.Scan()
		a, _ := strconv.Atoi(scanner.Text())
		scanner.Scan()
		f, _ := strconv.Atoi(scanner.Text())

		cnt[a] = true
		cnt_exp[a] = f % P_1
		cnt_mod[a] = f % P
		sum1[a] = (cnt_mod[a] * a) % P
		sum2[a] = (cnt_mod[a] * ((a * a) % P)) % P
	}

	mu := make([]int, MAXA)
	primes := make([]int, 0)
	isPrime := make([]bool, MAXA)
	for i := 2; i < MAXA; i++ {
		isPrime[i] = true
	}
	mu[1] = 1
	for i := 2; i < MAXA; i++ {
		if isPrime[i] {
			primes = append(primes, i)
			mu[i] = -1
		}
		for _, p := range primes {
			if i*p >= MAXA {
				break
			}
			isPrime[i*p] = false
			if i%p == 0 {
				mu[i*p] = 0
				break
			} else {
				mu[i*p] = -mu[i]
			}
		}
	}

	ans := 0
	for d := 1; d < MAXA; d++ {
		if mu[d] == 0 {
			continue
		}

		k_exp := 0
		k_mod := 0
		s1 := 0
		s2 := 0
		has_elements := false

		for j := d; j < MAXA; j += d {
			if cnt[j] {
				has_elements = true
				k_exp = (k_exp + cnt_exp[j]) % P_1
				k_mod = (k_mod + cnt_mod[j]) % P
				s1 = (s1 + sum1[j]) % P
				s2 = (s2 + sum2[j]) % P
			}
		}

		if !has_elements {
			continue
		}

		E := (k_exp - 3) % P_1
		if E < 0 {
			E += P_1
		}
		inv2 := power(2, E)

		term1 := (k_mod - 2 + P) % P
		term1 = (term1 * s2) % P

		term2 := (k_mod * s1) % P
		term2 = (term2 * s1) % P

		sum := (term1 + term2) % P
		sum = (sum * inv2) % P

		if mu[d] == -1 {
			ans = (ans - sum + P) % P
		} else if mu[d] == 1 {
			ans = (ans + sum) % P
		}
	}

	fmt.Println(ans)
}