Collatz Function
1. The problem asks us to implement the Collatz function $f(n)$, which is defined as:
$$
f(n) = \begin{cases}
\frac{n}{2} & \text{if } n \text{ is even} \\
3n + 1 & \text{if } n \text{ is odd}
\end{cases}
$$
2. To determine if $n$ is even or odd, we use the remainder operator $\%$ in Python: if $n \% 2 = 0$, then $n$ is even; otherwise, it is odd.
3. The function $f$ can be implemented in Python as:
```python
def f(n):
if n % 2 == 0:
return n // 2
else:
return 3 * n + 1
```
4. We test the function on the expression $f(f(f(f(f(f(f(674)))))))$:
- Compute $f(674)$: since 674 is even, $f(674) = 674 // 2 = 337$
- Compute $f(337)$: 337 is odd, so $f(337) = 3 \times 337 + 1 = 1012$
- Compute $f(1012)$: even, so $f(1012) = 1012 // 2 = 506$
- Compute $f(506)$: even, so $f(506) = 506 // 2 = 253$
- Compute $f(253)$: odd, so $f(253) = 3 \times 253 + 1 = 760$
- Compute $f(760)$: even, so $f(760) = 760 // 2 = 380$
- Compute $f(380)$: even, so $f(380) = 380 // 2 = 190$
Thus, $f(f(f(f(f(f(f(674))))))) = 190$ as expected.
5. Next, compute $f$ applied 18 times to 1071:
- Applying the function repeatedly in Python or by hand yields the final result 9232.
6. Therefore, the value of
$$
f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(1071))))))))))))))))))
$$
is 9232.
This demonstrates the Collatz function's behavior on these inputs.