```
x = 1
y = 1
prev_answer = 1
answer = None

while x <= 525:
answer = x*y + prev_answer + 3
print(f"{x = } ==> {answer = }")
x += 1
y += 1
prev_answer = answer
```

https://md.darknebu.la/4cDzvoArTDCD-hpjSmVTwQ?view#Fast-Enough

Original writeup (https://md.darknebu.la/4cDzvoArTDCD-hpjSmVTwQ?view#Fast-Enough).