View Compilation Error

0_0_20818002_402.cpp: In function 'int main()':
0_0_20818002_402.cpp:17:13: error: 'rec' was not declared in this scope
             rec[i] = ( a * rec[i-1] + b * rec[i-2] ) % 7;
             ^
0_0_20818002_402.cpp:29:18: error: 'rec' was not declared in this scope
            cout<<rec[beg+(n-end)%(end-beg)]<<endl;
                  ^
0_0_20818002_402.cpp:31:19: error: 'rec' was not declared in this scope
             cout<<rec[n]<<endl;
                   ^