## Problem 386

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Djinx
Posts: 5
Joined: Thu Dec 22, 2011 3:53 pm

### Problem 386

I understand it is perhaps too early to ask for help in this problem, but i would appreciate if someone who solved it comment on my values:

EDIT: Values removed, at least for the time.
Last edited by Djinx on Mon May 28, 2012 4:54 pm, edited 1 time in total.
hk
Posts: 11040
Joined: Sun Mar 26, 2006 10:34 am
Location: Haren, Netherlands

### Re: Problem 386

Djinx wrote:I understand it is perhaps too early to ask for help in this problem,
Yes it is by some weeks.
Djinx
Posts: 5
Joined: Thu Dec 22, 2011 3:53 pm

### Re: Problem 386

hk wrote:
Djinx wrote:I understand it is perhaps too early to ask for help in this problem,
Yes it is by some weeks.
Okay, then. Should I remove the post altogether?
hk
Posts: 11040
Joined: Sun Mar 26, 2006 10:34 am
Location: Haren, Netherlands

### Re: Problem 386

I leave that to your courtesy.
Djinx
Posts: 5
Joined: Thu Dec 22, 2011 3:53 pm

### Re: Problem 386

Considering that the number of solvers has already crossed the 100 mark, and the peculiarity of problems I am facing, I feel justified in asking for help one more time.

I could find a formula for the answer, and it does work perfectly fine against values I found against those by brute force for n=100, 1000, 10000. I also verified my code for some random values under 10^8. However, the final answer is still not accepted.

EDIT: It all turned out to be an overflow error . I apologize for my impatience.
Last edited by Djinx on Thu May 31, 2012 1:27 am, edited 1 time in total.
hk
Posts: 11040
Joined: Sun Mar 26, 2006 10:34 am
Location: Haren, Netherlands

### Re: Problem 386

Djinx wrote: I could find a formula for the answer, and it does work perfectly fine against values I found against those by brute force for n=100, 1000, 10000. I also verified my code for some random values under 10^8. However, the final answer is still not accepted.
That's a hallmark for overflow problems.
So if you could be so kind as to remove all information about the problem itself, i.e. your spelled out assumptions that would be great.
impulse
Posts: 1
Joined: Sat Jun 02, 2012 9:56 am

### Re: Problem 386

hk wrote: That's a hallmark for overflow problems.
Hi, I just want to know whether the solution is under the limit of 32 bits.
And can anyone provide a sample case please.
LarryBlake
Posts: 100
Joined: Sat Aug 29, 2009 8:49 pm

### Re: Problem 386

Can someone confirm if the maximal antichain for 120120 = 30?
thundre
Posts: 356
Joined: Sun Mar 27, 2011 10:01 am

### Re: Problem 386

Yes, the sum fits in 32 bits.
LarryBlake wrote:Can someone confirm if the maximal antichain for 120120 = 30?
Expand
edit: Hidden because it was WRONG.
Last edited by thundre on Thu Feb 07, 2013 1:43 pm, edited 1 time in total.
LarryBlake
Posts: 100
Joined: Sat Aug 29, 2009 8:49 pm

### Re: Problem 386

Okay, thanks.
LarryBlake
Posts: 100
Joined: Sat Aug 29, 2009 8:49 pm

### Re: Problem 386

Thundre, I just verified that my antichain of 30 elements contains no divisible numbers. Did you mean that 29 is the highest index starting at zero?

In any case, is it safe to say that there is no larger antichain for N(120120)?
thundre
Posts: 356
Joined: Sun Mar 27, 2011 10:01 am

### Re: Problem 386

LarryBlake wrote:Thundre, I just verified that my antichain of 30 elements contains no divisible numbers. Did you mean that 29 is the highest index starting at zero?

In any case, is it safe to say that there is no larger antichain for N(120120)?
30 is correct for 120120. I typed in 210210, which has a shorter maximal antichain.

LarryBlake
Posts: 100
Joined: Sat Aug 29, 2009 8:49 pm

### Re: Problem 386

No problem, thanks for the reply.

Guess I won't be in the first 100 solvers for this one.
tinnderbox
Posts: 3
Joined: Sun Nov 01, 2015 3:22 pm

### Problem 386

Hi,
since this problem is now nearly four years old and solved by over 400 the text is apparently clear enough.
Still, I was initially bemused for a few moments by the problem text.

The first line says
Let ...S(n) be the set of factors of n.
Then, a few lines lower:
For example: S(30) = {1, 2, 3, 5, 6, 10, 15, 30} \

Are the factors of 30 not {2,3,5} ?
Shouldn't the first line say: divisors ?
jaap
Posts: 554
Joined: Tue Mar 25, 2008 3:57 pm
Contact:

### Re: Problem 386

tinnderbox wrote:The first line says
Let ...S(n) be the set of factors of n.
Then, a few lines lower:
For example: S(30) = {1, 2, 3, 5, 6, 10, 15, 30} \

Are the factors of 30 not {2,3,5} ?
Shouldn't the first line say: divisors ?
Factor and Divisor mean the same thing in this context. {2,3,5} are the prime factors or prime divisors.