Sum Challenge

For discussing Olympiad Level Number Theory problems
User avatar
SANZEED
Posts:550
Joined:Wed Dec 28, 2011 6:45 pm
Location:Mymensingh, Bangladesh
Sum Challenge

Unread post by SANZEED » Fri Dec 30, 2011 9:29 am

Sum Challenge 001


Let the divisors of n be A={d1,d2,d3,….,dn} where
d1=1 and dn =n. Let Pd =∑i σ(di), d Є A, d/di.
Remember that σ(x)=sum of the divisors of x.

Prove that, I
∑d/n μ(d)Pd=1.
Attachments
Sum Challenge 001.doc
(19.5KiB)Downloaded 246 times
$\color{blue}{\textit{To}} \color{red}{\textit{ problems }} \color{blue}{\textit{I am encountering with-}} \color{green}{\textit{AVADA KEDAVRA!}}$

User avatar
Phlembac Adib Hasan
Posts:1016
Joined:Tue Nov 22, 2011 7:49 pm
Location:127.0.0.1
Contact:

Re: Sum Challenge

Unread post by Phlembac Adib Hasan » Fri Dec 30, 2011 11:54 am

SANZEED wrote:Sum Challenge 001


Let the divisors of n be A={d1,d2,d3,….,dn} where
d1=1 and dn =n. Let Pd =∑i σ(di), d Є A, d/di.
Remember that σ(x)=sum of the divisors of x.

Prove that, I
∑d/n μ(d)Pd=1.
The problem statement is confusing. Please clearly define $P_d$.Is it $P_{d_i} $? Otherwise it seems that $ P_d $ has only one value for every $n$.If you can't use LaTeX, then please explain it.
Welcome to BdMO Online Forum. Check out Forum Guides & Rules

User avatar
nafistiham
Posts:829
Joined:Mon Oct 17, 2011 3:56 pm
Location:24.758613,90.400161
Contact:

Re: Sum Challenge

Unread post by nafistiham » Fri Dec 30, 2011 2:24 pm

i was requested by SANZEED to latex his problem.unfortunately, now i myself don't understand what he wants to ask :oops: :oops:
\[\sum_{k=0}^{n-1}e^{\frac{2 \pi i k}{n}}=0\]
Using $L^AT_EX$ and following the rules of the forum are very easy but really important, too.Please co-operate.
Introduction:
Nafis Tiham
CSE Dept. SUST -HSC 14'
http://www.facebook.com/nafistiham
nafistiham@gmail

User avatar
SANZEED
Posts:550
Joined:Wed Dec 28, 2011 6:45 pm
Location:Mymensingh, Bangladesh

Re: Sum Challenge

Unread post by SANZEED » Sun Jan 22, 2012 6:17 am

YES,$p_{d}$ means $p_{d_{i}}$.let $d$ be adivisor of n.Then take the value of the divisors of n for $d_{i}$ which are divisible by $d$.

Moderation Note: $L^AT_EX$ed correctly.
$\color{blue}{\textit{To}} \color{red}{\textit{ problems }} \color{blue}{\textit{I am encountering with-}} \color{green}{\textit{AVADA KEDAVRA!}}$

User avatar
Phlembac Adib Hasan
Posts:1016
Joined:Tue Nov 22, 2011 7:49 pm
Location:127.0.0.1
Contact:

Re: Sum Challenge

Unread post by Phlembac Adib Hasan » Sun Jan 22, 2012 8:55 am

বড় সংখ্যার জন্য কাজ করতেসে না। ক্যালকুলেশনেই ভুল করলাম কিনা :?
Welcome to BdMO Online Forum. Check out Forum Guides & Rules

User avatar
SANZEED
Posts:550
Joined:Wed Dec 28, 2011 6:45 pm
Location:Mymensingh, Bangladesh

Re: Sum Challenge

Unread post by SANZEED » Wed Jan 25, 2012 12:21 am

Phlembac Adib Hasan wrote:বড় সংখ্যার জন্য কাজ করতেসে না। ক্যালকুলেশনেই ভুল করলাম কিনা :?
ADB! you should try vinogradov's theorem :lol: :lol: ;)
$\color{blue}{\textit{To}} \color{red}{\textit{ problems }} \color{blue}{\textit{I am encountering with-}} \color{green}{\textit{AVADA KEDAVRA!}}$

User avatar
SANZEED
Posts:550
Joined:Wed Dec 28, 2011 6:45 pm
Location:Mymensingh, Bangladesh

Re: Sum Challenge

Unread post by SANZEED » Thu Jan 26, 2012 7:29 am

Have you found errors?But I checked my use of Vinogradov's......now Iam also confused....
$\color{blue}{\textit{To}} \color{red}{\textit{ problems }} \color{blue}{\textit{I am encountering with-}} \color{green}{\textit{AVADA KEDAVRA!}}$

Post Reply