When number of primes of the form $3k+1$ and $3k-1$ are the same

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Let's denote the number of prime numbers of the form $3k+1$ which are not greater than $x$ with $\pi _{3k+1}(x)$. Similarly let's denote the number of prime numbers of the form $3k-1$ which are not greater than $x$ with $\pi _{3k-1}(x)$.

1) Are there infinitely integers $x$ such as $\pi _{3k+1}(x)=\pi _{3k-1}(x)$?

2) How often $\pi _{3k+1}(x)=\pi _{3k-1}(x)$ is true? Can we find an asymptotic formula for this?

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See the paper Chebyshev's Conjecture and the Prime Number Race, by Kevin Ford and Sergei Konyagin. The last paragraph on the first page answers your first question: the quantity $\pi_{3k+1}(x)-\pi_{3k-1}(x)$ changes sign infinitely often, so it must equal zero infinitely often.

I don't have any suggestions for your second question. As Giovanni Resta comments, these problems are difficult.

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There are arbitrarily large $x$ so that $\pi_{3k+1}(x) > \pi_{3k-1}(x)$, and arbitrarily large $x$ so that $\pi_{3k+1}(x) < \pi_{3k-1}(x)$. And thus there are infinitely many $x$ such that $\pi_{3k+1}(x) = \pi_{3k-1}(x)$. However, $\pi_{3k-1}(x)$ is larger far more often. Asymptotically, the percentage of time that $\pi_{3k-1}(x)$ is larger approaches $100$% as $x \to \infty$. This does not give an asymptotic for the number of times they agree up to some $X$, of course. It's just rather interesting.

This was the subject of a 1914 paper from Littlewood, and I'm distilling information from that paper.