Brain Teasers
0, 1, 1, 3, 1, 6, 1, 7, 4, 8, ?, ?, ?
0, 1, 1, 3, 1, 6, 1, 7, 4, 8, ?, ?, ?
Hint
Which terms are 1?Answer
1, 16, 1.The nth term is the sum of the proper divisors of n. The prime numbers have 1 as their only proper divisor.
Hide Hint Show Hint Hide Answer Show Answer
What Next?
View a Similar Brain Teaser...
If you become a registered user you can vote on this brain teaser, keep track of which ones you have seen, and even make your own.
Solve a Puzzle
Comments
I think the primes should be 2, not 1 - the divisors are 1 and the number itself. In any event it is not consistent to list the number of divisors for entry 4 as "3", because that would have to include 1, 2, and 4 - i.e., the number itself. Thus for consistency, the primes should all be listed as "2".
Never mind - I reread your wording and understand my mistake now. "Sum" of the divisors - you are correct, as usual!
Neat. I couldn't figure this one out.
To post a comment, please create an account and sign in.
Follow Braingle!