题解 | 智乃的数字

//3 9 15 21 27 33 39 45 51 57 63 69 75
//5 15 25 35 45 55 65 75
//3 5 9 15 21 25 27 33 35 39 45 51 55 57 63 65 69 75
//1 2 3 4  5  6  7  8  9  10 11 12 13 14 15 16 17 18
#include<iostream>
#define int long long 

using namespace std;

int sn[5]={0,3,5,9,15};
int t;
int k;

signed main()
{
    cin>>t;
    while(t--)
    {
        cin>>k;
        int id=(k-4)/7;
        if(k>4) id++;
        if(id==0) cout<<sn[k]<<endl;
        else
        {
            int tmp=(k-4)%7;
            //cout<<tmp<<endl;
            if(tmp==0) cout<<15+30*(id-1)<<endl;
            else if(tmp==1) cout<<15+30*(id-1)+6<<endl;
            else if(tmp==3 || tmp==4) cout<<15+30*(id-1)+6*tmp-6<<endl;
            else if(tmp==6) cout<<15+30*(id-1)+6*tmp-12<<endl;
            else if(tmp==2) cout<<15+30*(id-1)+10<<endl;
            else cout<<15+30*(id-1)+20<<endl;
        }
    }
    return 0;
}