• No sample tests

• No random tests

I thought this is very nice solution but times out. I can only think of finding a way to speed up the search for prime numbers

when you use return(), this will end your function so you do not need to use break

Nice solution, except those hard coded dates in your code

It would be nicer if you avoided hardcoding the dates in the function, in this case end of Trump presidency. You could have added 8 years (or 4 years) to Trump's innauguration to mark end of his presidency.

I did not know you could load packages. I'd suggest arranging the data by innauguration date just as precaution. I like the use of map_chr(). Check my solution; I used only base-R.

Merge conflict. I suggest this solution:
if (length(nums) == 0) 0 else sum(nums^2)

Nicely done. Just wanted to say you don't need the second collapse argument