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Search: MSC category 11A25 ( Arithmetic functions; related numbers; inversion formulas )

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1. CMB 2009 (vol 52 pp. 3)

Banks, W. D.
 Carmichael Numbers with a Square Totient Let $\varphi$ denote the Euler function. In this paper, we show that for all large $x$ there are more than $x^{0.33}$ Carmichael numbers $n\le x$ with the property that $\varphi(n)$ is a perfect square. We also obtain similar results for higher powers. Categories:11N25, 11A25

2. CMB 2008 (vol 51 pp. 3)

3. CMB 2005 (vol 48 pp. 211)

Germain, Jam
 The Distribution of Totatives The integers coprime to $n$ are called the {\it totatives} \rm of $n$. D. H. Lehmer and Paul Erd\H{o}s were interested in understanding when the number of totatives between $in/k$ and $(i+1)n/k$ are $1/k$th of the total number of totatives up to $n$. They provided criteria in various cases. Here we give an if and only if'' criterion which allows us to recover most of the previous results in this literature and to go beyond, as well to reformulate the problem in terms of combinatorial group theory. Our criterion is that the above holds if and only if for every odd character $\chi \pmod \kappa$ (where $\kappa:=k/\gcd(k,n/\prod_{p|n} p)$) there exists a prime $p=p_\chi$ dividing $n$ for which $\chi(p)=1$. Categories:11A05, 11A07, 11A25, 20C99

4. CMB 2002 (vol 45 pp. 109)

Hall, R. R.; Shiu, P.
 The Distribution of Totatives D.~H.~Lehmer initiated the study of the distribution of totatives, which are numbers coprime with a given integer. This led to various problems considered by P.~Erd\H os, who made a conjecture on such distributions. We prove his conjecture by establishing a theorem on the ordering of residues. Keywords:Euler's function, totativesCategories:11A05, 11A07, 11A25

5. CMB 1997 (vol 40 pp. 498)

Selvaraj, Chikkanna; Selvaraj, Suguna
 Matrix transformations based on Dirichlet convolution This paper is a study of summability methods that are based on Dirichlet convolution. If $f(n)$ is a function on positive integers and $x$ is a sequence such that $\lim_{n\to \infty} \sum_{k\le n} {1\over k}(f\ast x)(k) =L$, then $x$ is said to be {\it $A_f$-summable\/} to $L$. The necessary and sufficient condition for the matrix $A_f$ to preserve bounded variation of sequences is established. Also, the matrix $A_f$ is investigated as $\ell - \ell$ and $G-G$ mappings. The strength of the $A_f$-matrix is also discussed. Categories:11A25, 40A05, 40C05, 40D05