View Compilation Error

0_0_21699636_24474.cpp: In function 'int main()':
0_0_21699636_24474.cpp:6:2: error: '_int64' was not declared in this scope
  _int64 a[51]={0,3,6,6}; 
  ^
0_0_21699636_24474.cpp:8:3: error: 'a' was not declared in this scope
   a[i]=a[i-1]+2*a[i-2]; 
   ^
0_0_21699636_24474.cpp:10:20: error: 'a' was not declared in this scope
   printf("%I64d\n",a[n]); 
                    ^