- #1

sigh1342

- 31

- 0

find the least n s.t. f(n) is divisible by 17 , I have no idea about it.

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- Thread starter sigh1342
- Start date

- #1

sigh1342

- 31

- 0

find the least n s.t. f(n) is divisible by 17 , I have no idea about it.

- #2

mfb

Mentor

- 36,291

- 13,366

What is the remainder if you divide...

1 by 17?

10 by 17?

100 by 17?

...

a+b by 17, if you know it for a and b?

That should help.

- #3

ramsey2879

- 841

- 3

find the least n s.t. f(n) is divisible by 17 , I have no idea about it.

It should also help to recognize that 9 times the sum plus 1 is a power of 10. Thus Fermats Little theorem re primes P dividing A^(P-1) - 1 may apply.

- #4

Edgardo

- 705

- 15

You can also find n by "brute force", i.e. check if f(1), f(2), f(3), ... is divisible by 17. Use http://www.wolframalpha.com/ or write a small program in your programming language of choice.

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