本人使用矩阵乘法试图解决本题，但无法找到 Bug 且 $0$ 分，求调！

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define MOD 19260817
int n,k;
struct matrix
{
    int p[5][5];
    matrix operator * (const matrix d) const
    {
        matrix g;
        memset(g.p,0,sizeof(g.p));
        for(int i = 1ll;i <= n;i++)
        {
            for(int j = 1ll;j <= n;j++)
            {
                for(int k = 1ll;k <= n;k++)
                {
                    g.p[i][j] = (g.p[i][j] + (d.p[i][k] * p[k][j]) % MOD) % MOD;
                    g.p[i][j] %= MOD;
                }
            }
        }
        return g;
    }
    void operator = (matrix d)
    {
        for(int i = 1ll;i <= n;i++)
        {
            for(int j = 1ll;j <= n;j++)
            {
                p[i][j] = d.p[i][j];
            }
        }
    }
} ans,zer0,p;
void output(matrix r)
{
    for(int i = 1ll;i <= n;i++)
    {
        for(int j = 1ll;j <= n;j++)
        {
            cout << r.p[i][j] << " ";
        }
        cout << endl;
    }
}
void read(matrix &b)
{
    for(int i = 1ll;i <= n;i++)
    {
        for(int j = 1ll;j <= n;j++)
        {
            cin >> b.p[i][j];
        }
    }
}
void init(matrix &a,int l)
{
    for(int i = 1ll;i <= n;i++)
    {
        for(int j = 1ll;j <= n;j++)
        {
            a.p[i][j] = l;
        }
    }
}
matrix ksm(int kkk)
{
    matrix tmp;
    tmp.p[1][1] = 7;
    tmp.p[1][2] = 4;
    tmp.p[1][3] = 2;
    tmp.p[2][1] = 0;
    tmp.p[2][2] = 0;
    tmp.p[2][3] = 0;
    tmp.p[3][1] = 0;
    tmp.p[3][2] = 0;
    tmp.p[3][3] = 0;
    for(int i = 0;i < 31;i++,p = p * p)
    {
        if(kkk & (1 << i)) tmp = tmp * p;
    }
    return tmp;
}
signed main()
{
	//freopen("1.in","r",stdin);
	//freopen("1.out","w",stdout);
    p.p[1][1] = 1;
    p.p[1][2] = 1;
    p.p[1][3] = 1;
    p.p[2][1] = 1;
    p.p[2][2] = 0;
    p.p[2][3] = 0;
    p.p[3][1] = 0;
    p.p[3][2] = 1;
    p.p[3][3] = 0;
    for(int i = 1;i <= n;i++)
    {
        for(int j = 1;j <= n;j++)
        {
            zer0.p[i][j] = (i == j);
        }
    }
	int t;
    cin >> t;
    while(t--)
    {
        n = 3;
        cin >> k;
        if(k == 1)
        {
            cout << "2\n";
            continue;
        }
        if(k == 2)
        {
            cout << "4\n";
            continue;
        }
        if(k == 3)
        {
            cout << "7\n";
            continue;
        }
        matrix hhh = ksm(k - 3);
        //output(hhh);
        cout << (hhh.p[1][1] + hhh.p[1][2]) % 19260817 << endl;
    }
    return 0;
}