Erdős, Paul; Straus, E. G. On the irrationality of certain series. (English) Zbl 0279.10026 Pac. J. Math. 55(1974), 85-92 (1973). A criterion is established for the rationality of series of the form \(\sum b_n/a_1 \ldots a_n\) where \(a_n,b_n\) are integers, \(a_n \geq 2\) and \(\lim b_n/(a_{n-1}a_n)=0\). This criterion is applied to prove the irrationality and rational independence of certain special series of the above type. Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 3 ReviewsCited in 15 Documents MSC: 11J81 Transcendence (general theory) PDF BibTeX XML Cite \textit{P. Erdős} and \textit{E. G. Straus}, Pac. J. Math. 55, 85--92 (1974; Zbl 0279.10026) Full Text: DOI OpenURL Online Encyclopedia of Integer Sequences: Decimal expansion of Sum_{n>=1} phi(n)/n!, where phi(n) is the Euler totient function A000010.