### 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.

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## 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.

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