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CrossRef Open Access 2025
Summatory Multiplicative Arithmetic Functions: Scaling and Renormalization

Leonid G. Fel

We consider a wide class of summatory functions Ff;N,pm=∑k≤Nfpmk, m∈Z+∪{0} associated with the multiplicative arithmetic functions f of a scaled variable k∈Z+, where p is a prime number. Assuming an asymptotic behavior of the summatory function, F{f;N,1}=N→∞G1(N)1+OG2(N), where G1(N)=Na1logNb1, G2(N)=N−a2logN−b2 and a1,a2≥0, −∞<b1,b2<∞, we calculate the renormalization function Rf;N,pm, defined as a ratio Ff;N,pm/F{f;N,1}, and find its asymptotics R∞f;pm when N→∞. We prove that a renormalization function is multiplicative, i.e., R∞f;∏i=1npimi=∏i=1nR∞f;pimi with n distinct primes pi. We extend these results to the other summatory functions ∑k≤Nf(pmkl), m,l,k∈Z+ and ∑k≤N∏i=1nfikpmi, fi≠fj, mi≠mj. We apply the derived formulas to a large number of basic summatory functions including the Euler ϕ(k) and Dedekind ψ(k) totient functions, divisor σn(k) and prime divisor β(k) functions, the Ramanujan sum Cq(n) and Ramanujan τ Dirichlet series, and others.

CrossRef Open Access 2025
On the Arithmetic Average of the First n Primes

Matt Visser

The arithmetic average of the first n primes, p¯n=1n∑i=1npi, exhibits very many interesting and subtle properties. Since the transformation from pn→p¯n is extremely easy to invert, pn=np¯n−(n−1)p¯n−1, it is clear that these two sequences pn⟷p¯n must ultimately carry exactly the same information. But the averaged sequence p¯n, while very closely correlated with the primes, (p¯n∼12pn), is much “smoother” and much better behaved. Using extensions of various standard results, I shall demonstrate that the prime-averaged sequence p¯n satisfies prime-averaged analogues of the Cramer, Andrica, Legendre, Oppermann, Brocard, Fourges, Firoozbakht, Nicholson, and Farhadian conjectures. (So these prime-averaged analogues are not conjectures; they are theorems). The crucial key to enabling this pleasant behaviour is the “smoothing” process inherent in averaging. While the asymptotic behaviour of the two sequences is very closely correlated, the local fluctuations are quite different.

DOAJ Open Access 2008
Zonder historisch perspectief van crisis naar crisis

Arnoud W. A. Boot

Begrijpen we de economie of rennen we alleen maar achter modeverschijnselen aan? Schumpeter, in zijn postuum gepubliceerde standaardwerk History of Economic Analysis, had het ideaal dat het vak economie ontdaan zou kunnen worden van de maatschappelijke en historische context. Hij formuleerde het als ‘het [het vak economie] zal eindelijk dezelfde dienst voor de economische politiek opleveren als de theoretische natuurkunde voor de werktuigbouw’. Heel mooi, maar misschien toch een tikkeltje naïef. We zijn telken - male op zoek naar wetmatigheden, maar die zijn toch wat minder grijpbaar dan de natuurkrachten in de natuurkunde… En niet alleen minder grijpbaar, maar ook sterk onderhevig aan maatschappelijke ontwikkelingen en misschien wel modeverschijnselen.

Business, Business mathematics. Commercial arithmetic. Including tables, etc.

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