Grosswald, Emil The average order of an arithmetic function. (English) Zbl 0070.27501 Duke Math. J. 23, 41-44 (1956). Let \(F(n)\) denote the number of all prime divisors of \(n\), distinct or not. The author proves that \[ \sum_{_{\substack{ n\leq x\\ 2\nmid n}}} 2^{F(n)}= c_2x\log x-c_5 x+O(x^\varepsilon), \] where \(c_2\) and \(c_5\) are constants and \(c<0.84\). In the proof he uses the property that \(\zeta(s)=O\left(| t|^{1/2(L-1)+\varepsilon}\right)\) holds uniformly for \(\sigma\geq 1-l/2(L-1)\) and any \(\varepsilon>0\), where \(l\) is an integer \(\geq 3\) and \(L=2^{l-1}\). For nonintegral value \(l\) (as the author uses \(l=3.54\ldots\)), the previous result needs a proof. Reviewer: Loo-Keng Hua (Beijing) Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 1 ReviewCited in 5 Documents MSC: 11N37 Asymptotic results on arithmetic functions Keywords:average order; arithmetic function Citations:Zbl 0055.27503 × Cite Format Result Cite Review PDF Full Text: DOI Online Encyclopedia of Integer Sequences: a(n) = Sum_{k=1..n} 2^bigomega(k). Decimal expansion of Selberg-Delange constant Product_{prime p > 2} (1 + 1/(p(p-2))) Decimal expansion of Sum_{primes p > 2} log(p) / ((p-2)*(p-1)).