View Compilation Error

0_0_22894658_19598.cpp: In function 'int main()':
0_0_22894658_19598.cpp:16:22: error: 'f' cannot be used as a function
     f[i]=(a * f(n - 1) + b * f(n - 2))%7; 
                      ^
0_0_22894658_19598.cpp:16:37: error: 'f' cannot be used as a function
     f[i]=(a * f(n - 1) + b * f(n - 2))%7; 
                                     ^