On the distribution of primes in the alternating sums of concecutive primes

Abstract

Quite recently, in [8] the authoor of this paper considered the distribution of primes in the sequence $(S_n)$ whose $n$th term is defined as $S_n=\sum_{k=1}^{2n}p_k$, where $p_k$ is the $k$th prime. Some heuristic arguments and the numerical evidence lead to the conjecture that the primes are distributed among sequence $(S_n)$ in the same way that they are distributed among positive integers. More precisely, Conjecture 3.3 in [8] asserts that $\pi_n\sim \frac{n}{\log n}$ as $n\to \infty$, where $\pi_n$ denotes the number of primes in the set $\{S_1,S_2,\ldots, S_n\}$. Motivated by this, here we consider the distribution of primes in aletrnating sums of first $2n$ primes, i.e., in the sequences $(A_n)$ and $(T_n)$ defined by $A_n:=\sum_{i=1}^{2n}(-1)^ip_i$ and $T_n:=A_n-2=\sum_{i=2}^{2n}(-1)^ip_i$ ($n=1,2,\ldots$). Heuristic arguments and computational results suggest the conjecture that (Conjecture 2.5) $$ \pi_{(A_k)}(A_n)\sim \pi_{(T_k)}(T_n)\sim \frac{2n}{\log n} \quad {\rm as}\,\, n\to \infty, $$ where $\pi_{(A_k)}(A_n)$ (respectively, $\pi_{(T_k)}(T_n)$) denotes the number of primes in the set $\{A_1,A_2,\ldots, A_n\}$(respectively, $\{T_1,T_2,\ldots, T_n\}$). Under Conjecture 2.5 and Pillai's conjecture, we establish two results concerning the expressions for the $k$th prime in the sequences $(A_n)$ and $(T_n)$. Furthermore, we propose some other related conjectures and we deduce some their consequences.