#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<map>
#include<queue>
#include<bitset>
#include<set> 
#define int long long
#define lowbit(x) x&(-x)
#define mp make_pair
#define rep(i,x,n) for(int i=x;i<=n;i++)
#define per(i,n,x) for(int i=n;i>=x;i--)
#define forE(i,x) for(int i=head[x];i;i=nxt[i])
#define pii pair<int,int>
#define fi first
#define se second
using namespace std;
const int maxn=2e5+5;
const int mod=998244353;
inline int read()
{
	int x=0,f=1;char c=getchar();
	while(c<'0'||c>'9')
	{
		if(c=='-') f=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9')
	{
		x=x*10+(c-'0');
		c=getchar();
	}
	return x*f;
}
int T;
int a[maxn];
signed main()
{
	T=read();
	while(T--)
	{
		int n=read();
		rep(i,1,n) a[i]=read();
		rep(i,2,n) a[i]=(a[i]+a[i-1])%mod+(a[i]*a[i-1])%mod,a[i]%=mod;
		printf("%lld\n",a[n]);
	}
}