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Erdős’s Work on the Sum of Divisors Function and on Euler’s Function

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Book cover Erdős Centennial

Part of the book series: Bolyai Society Mathematical Studies ((BSMS,volume 25))

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Abstract

The following notation will be used throughout

log r x is the r times iterated logarithm of x,

$$\begin{gathered}\sigma _1 (n) = \sigma (n),\quad \sigma _k (n) = \sigma (\sigma _{k - 1} (n)), \hfill \\\phi _1 (n) = \phi (n),\quad \phi _k (n) = \phi (\phi _{k - 1} (n)), \hfill \\s_1 (n) = s(n) = \quad \sigma (n) - n,\quad s_i (n) = s_1 (s_{i - 1} (n)); \hfill \\\end{gathered}$$

ψ is Euler’s constant, \(\alpha _0 = \log \Pi _p \;prime\;(1 - \frac{1}{p})^{ - 1/p}\). Density is always the asymptotic density.

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© 2013 János Bolyai Mathematical Society and Springer-Verlag

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Schinzel, A. (2013). Erdős’s Work on the Sum of Divisors Function and on Euler’s Function. In: Lovász, L., Ruzsa, I.Z., Sós, V.T. (eds) Erdős Centennial. Bolyai Society Mathematical Studies, vol 25. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-39286-3_21

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