Derived Ramanujan Primes : R'_{n}

Abstract

We study the Ramanujan-prime-counting function along the lines of Ramanujan's original work on Bertrand's Postulate. We show that the number of Ramanujan primes between x and 2x tends to infinity with x. This analysis leads us to define a new sequence of prime numbers, which we call derived Ramanujan primes. For n greater than or equal to 1 we define the nth derived Ramanujan prime as the smallest positive integer with the property that if x is greater than or equal to the nth derived Ramanujan prime, then the number of Ramanujan primes in the interval from x to x/2 is greater than or equal to n. As an application of the existence of derived Ramanujan primes, we prove analogues for Ramanujan primes of Richert's Theorem and Greenfield's Theorem for primes. We give some new inequalities for both the prime-counting function and for the Ramanujan-prime-counting function. Following the recent works of Sondow and Laishram on the bounds of Ramanujan primes, we analyze the bounds of derived Ramanujan primes. Finally, we give another proof of the theorem of Amersi, Beckwith, Miller, Ronan and Sondow.