#include<bits/stdc++.h>
#define ll long long
#define int long long
using namespace std;
const int mod=998244353;
const int N=1000000;
int fac[N+10],rev[N+10];
int powmod(int x,int y){
    int re=1;
    while(y){
        if(y&1) re=1ll*re*x%mod;
        y>>=1;
        x=1ll*x*x%mod;
    }
    return re;
}
int C(int x,int y){
    return 1ll*fac[x]*rev[x-y]%mod*rev[y]%mod;
}
int n,k;
void solve(){
    scanf("%lld%lld",&n,&k);
    ll ans=0;
    if(n==1){
        for(int i=n+1;i<=n+k;i++){
            ans+=i;
        }
        ans=ans%mod;
        printf("%lld\n",ans);
        return ;
    }
    for(int p=2*(n-1);p<=n+k;p++){
        ans=(ans+1ll*(n-1)*fac[p-n]%mod*rev[p-1]%mod*p%mod*fac[n-2]%mod*C((int)(p/2),n-1)%mod)%mod;
        ans=(mod+ans-2ll*(n-1)*fac[p-n]%mod*rev[p-1]%mod*fac[n-1]%mod*C((int)(p/2)+1,n)%mod)%mod;
//        cout<<p<<" "<<ans<<endl;
    }
    printf("%lld\n",ans*n%mod);
}
signed main(){
    fac[0]=1;
    for(int i=1;i<=N;i++){
        fac[i]=1ll*fac[i-1]*i%mod;
    }
    rev[N]=powmod(fac[N],mod-2);
    for(int i=N;i>0;i--){
        rev[i-1]=1ll*rev[i]*i%mod;
    }
    int t;
    cin>>t;
    while(t--){
        solve();
    }
    return 0;
}
/*
8
1 1
1 2
2 1
2 2
3 1
3 2
3 3
4 3


666
*/