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E-symmetric numbers

Gang Yu (2005)

Colloquium Mathematicae

A positive integer n is called E-symmetric if there exists a positive integer m such that |m-n| = (ϕ(m),ϕ(n)), and n is called E-asymmetric if it is not E-symmetric. We show that there are infinitely many E-symmetric and E-asymmetric primes.

Generalizing a theorem of Schur

Lenny Jones (2014)

Czechoslovak Mathematical Journal

In a letter written to Landau in 1935, Schur stated that for any integer t > 2 , there are primes p 1 < p 2 < < p t such that p 1 + p 2 > p t . In this note, we use the Prime Number Theorem and extend Schur’s result to show that for any integers t k 1 and real ϵ > 0 , there exist primes p 1 < p 2 < < p t such that p 1 + p 2 + + p k > ( k - ϵ ) p t .

Inequalities concerning the function π(x): Applications

Laurenţiu Panaitopol (2000)

Acta Arithmetica

Introduction. In this note we use the following standard notations: π(x) is the number of primes not exceeding x, while θ ( x ) = p x l o g p . The best known inequalities involving the function π(x) are the ones obtained in [6] by B. Rosser and L. Schoenfeld: (1) x/(log x - 1/2) < π(x) for x ≥ 67 (2) x/(log x - 3/2) > π(x) for x > e 3 / 2 . The proof of the above inequalities is not elementary and is based on the first 25 000 zeros of the Riemann function ξ(s) obtained by D. H. Lehmer [4]. Then Rosser, Yohe and Schoenfeld...

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