View Compilation Error

0_0_24252009_28570.cpp: In function 'int main()':
0_0_24252009_28570.cpp:6:5: error: '_int64' was not declared in this scope
     _int64 a[36] = {1};
     ^
0_0_24252009_28570.cpp:10:9: error: 'a' was not declared in this scope
         a[i + 1] = 1.0 * (2 * i + 1) / (i + 2) * a[i] * 2;
         ^
0_0_24252009_28570.cpp:15:45: error: 'a' was not declared in this scope
         printf("%d %d %I64d\n", index++, n, a[n] * 2);
                                             ^