View Compilation Error

0_0_39063559_31.c: In function 'main':
0_0_39063559_31.c:13:9: error: 'f1' undeclared (first use in this function); did you mean 'y1'?
   13 |         f1[n]=(__int64)pow((float)4,n-2)-(__int64)pow((float)2,n-2)-f2[n-1]+f3[n-1];
      |         ^~
      |         y1
0_0_39063559_31.c:13:9: note: each undeclared identifier is reported only once for each function it appears in
0_0_39063559_31.c:13:69: error: 'f2' undeclared (first use in this function)
   13 |         f1[n]=(__int64)pow((float)4,n-2)-(__int64)pow((float)2,n-2)-f2[n-1]+f3[n-1];
      |                                                                     ^~
0_0_39063559_31.c:13:77: error: 'f3' undeclared (first use in this function)
   13 |         f1[n]=(__int64)pow((float)4,n-2)-(__int64)pow((float)2,n-2)-f2[n-1]+f3[n-1];
      |                                                                             ^~