Vestnik Tomskogo Gosudarstvennogo Universiteta. Matematika i Mekhanika
RUS  ENG    JOURNALS   PEOPLE   ORGANISATIONS   CONFERENCES   SEMINARS   VIDEO LIBRARY   PACKAGE AMSBIB  
General information
Latest issue
Archive
Impact factor

Search papers
Search references

RSS
Latest issue
Current issues
Archive issues
What is RSS



Vestn. Tomsk. Gos. Univ. Mat. Mekh.:
Year:
Volume:
Issue:
Page:
Find






Personal entry:
Login:
Password:
Save password
Enter
Forgotten password?
Register


Vestnik Tomskogo Gosudarstvennogo Universiteta. Matematika i Mekhanika, 2014, Number 6(32), Pages 5–18 (Mi vtgu423)  

MATHEMATICS

On odd perfect numbers

R. Z. Ahmadullin

Bashkir State Pedagogical University named after M. Akmulla, Ufa, Russian Federation
References:
Abstract: A perfect number is a natural number equal to the sum of all its proper divisors (all positive divisors other than the number itself). Perfect numbers form a sequence: $6, 28, 496, 8128, 33550336, 8589869056, 137438691328~\dots$
Let $S=p_1^{a_1}\cdot p_2^{a_2}\cdots p_{n-1}^{a_{n-1}}\cdot p_n^{a_n}$ be a perfect number, where $p_i$ are primes, $a_i$ are some natural numbers, $a_i\geqslant 1$, $i=1, \dots, n$, and $n$ is the number of factors of the number $S$. Then
\begin{equation} \frac{p_1^{1+a_1}-1}{(p_1-1)p_1^{a_1}}\cdot \frac{p_2^{1+a_2}-1}{(p_2-1)^*p_2^{a_2}}\cdots \frac{p_n^{1+a_n}-1}{(p_n-1)^*p_n^{a_n}}=2. \end{equation}

Equation (1) is a Diophantine equation with an indefinite number of unknowns; it contains $2n$ unknowns, the value of $n$ (the number of factors of the number) is not fixed. This equation is equivalent to the two systems:
\begin{equation} \left\{\begin{aligned} p_1=&\frac1{\mathcal{Q}_1-1}\geqslant2, &a_1=\frac{-\ln(\mathcal{Q}_1-p_1(\mathcal{Q}_1-1))}{\ln(p_1)}\geqslant1;\\ & &\dots;\\ p_n=&\frac1{\mathcal{Q}_n-1}\geqslant p(n), & a_n=\frac{-\ln(\mathcal{Q}_n-p_n(\mathcal{Q}_n-1))}{\ln(p_n)}\geqslant1,\\ \end{aligned}\right. \end{equation}
where
$$ \begin{gathered} \mathcal{Q}_i=2\frac{(p_1-1)p_1^{a_1}}{p_1^{1+a_1}-1}\cdots \frac{(p_{i-1}-1)p_{i-1}^{a_{i-1}}}{p_{i-1}^{1+a_{i-1}}-1}\cdot \frac{(p_{i+1}-1)p_{i+1}^{a_{i+1}}}{p_{i+1}^{1+a_{i+1}}-1}\cdots \frac{(p_n-1)p_n^{a_n}}{p_n^{1+a_n}-1}=\\ =2\prod_{j=1}^{n\backslash i}\frac{(p_j-1)p_j^{a_j}}{p_j^{1+a_j}-1};\quad i=1,\dots,n, \end{gathered} $$
and
\begin{equation} \left\{\begin{aligned} \frac{p_1^{1+a_1}-1}{(p_1-1)}=&2^{\delta(a_1,p_1)}\prod_{j=1}^{n\backslash1}p_i^{a^{(1,j)}(a_1,p_1)};\dots;\\ \frac{p_n^{1+a_n}-1}{(p_n-1)}=&2^{\delta(a_n,p_n)}\prod_{j=1}^{n-1}p_i^{a^{(n,j)}(a_n,p_n)};\quad \sum_{j=1}^n a^{(j)}=a_i; \quad i=1,\dots,n, \end{aligned} \right. \end{equation}
where $\delta(a_1,p_1)$ is formally defined as follows:
$$ \delta(a_1,p_1)= \begin{cases} 0, & \text{ if } p_1=2,\\ 0, &\text{ if } p_1\ne2 \text{ and } a_1\text{- even},\\ 1, &\text{ if } p_1\ne2 \text{ and } a_1\text{- odd}. \end{cases} $$

With allowance for the fact that the factorization of natural numbers is determined uniquely, the system of equations (5) is a system of $2n$ equations and $2n$ unknowns (not with $(n^2+n)$ unknowns). The numbers $a^{(i,j)}$ are uniquely determined by a factorization function $F(p_1,a_1,i,j)$ and are considered as parameters.
From the system of equations (2) we obtain the equation
\begin{equation} a=-\frac{\ln\left(q-\frac1{q-1}(q-1)\right)^{-1}}{\ln\frac1{q-1}} \end{equation}
at $2>q>1$. This function has an infinite number of (infinite) left discontinuities of the second kind at the points $q=(l+1)/1$ ($l\in\mathrm{N}$). Hypothetically, beginning from some values of $n$, most of exponents of $a_n$ in system (2) can be equal only to $1$.
It is proved that for a given (fixed) value $n\geqslant3$ there exists only a finite number of odd perfect numbers.
Keywords: odd perfect number, amicable numbers, number theory.
Received: 02.02.2014
Document Type: Article
UDC: 511.2
Language: Russian
Citation: R. Z. Ahmadullin, “On odd perfect numbers”, Vestn. Tomsk. Gos. Univ. Mat. Mekh., 2014, no. 6(32), 5–18
Citation in format AMSBIB
\Bibitem{Ahm14}
\by R.~Z.~Ahmadullin
\paper On odd perfect numbers
\jour Vestn. Tomsk. Gos. Univ. Mat. Mekh.
\yr 2014
\issue 6(32)
\pages 5--18
\mathnet{http://mi.mathnet.ru/vtgu423}
Linking options:
  • https://www.mathnet.ru/eng/vtgu423
  • https://www.mathnet.ru/eng/vtgu/y2014/i6/p5
  • Citing articles in Google Scholar: Russian citations, English citations
    Related articles in Google Scholar: Russian articles, English articles
    Вестник Томского государственного университета. Математика и механика
    Statistics & downloads:
    Abstract page:230
    Full-text PDF :110
    References:31
     
      Contact us:
     Terms of Use  Registration to the website  Logotypes © Steklov Mathematical Institute RAS, 2024