Final answer:
To find the 20th term in the sequence, start with 7 and follow the given rule by cubing the digits in the previous term.
Hence, the 20th term in the sequence is 448.
Step-by-step explanation:
To find the 20th term in the sequence, we need to follow the given rule: each term after the first is found by taking the sum of the cubes of the digits in the previous term.
We start with 7, so the first term is 7.
To find the second term, we cube each digit of 7 (which is only one digit) to get 343.
Continuing this process, we find the third term by cubing each digit of 343 to get 448.
We repeat this process until we find the 20th term.
By following these steps, we find that the 20th term in the sequence is 448.