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I can prove that given $ε$ chosen arbitrarily small, if $\prod_{p \le p_k} p^{\frac{1}{p-1}} \lt \frac{1 + ε}{e} p_k$ then $∀n\ge p_k∃p∈\mathbb{P} | n \le p \lt (1 + ε)n$.

Actually this result is better than Bertrand's Postulate. And I've seen this paper which has a worser result.

But how much is this result notable? If so, how and where do I publish it?

EDIT

In my first post I've made a huge mistake: I've written a sum instead of a product! Now it's correct.

EDIT

By GHfromMO's answer, it's clear that $ε$ has a lower bound. But is this result anyway notable? If so, where and how can I publish it?

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    $\begingroup$ Note that the paper you linked to has not been published in any peer reviewed journal. $\endgroup$ Commented Feb 9, 2018 at 15:57
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    $\begingroup$ Do you have a value of k for which your product inequality holds? I am computing for small k and have found none. Gerhard "Truth Sometimes Comes From Emptiness" Paseman, 2018.02.09. $\endgroup$ Commented Feb 9, 2018 at 17:02
  • $\begingroup$ @GerhardPaseman For ε = 1, k = 12 is sufficient. $\endgroup$ Commented Feb 9, 2018 at 17:04
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    $\begingroup$ The problem with your (corrected) result is that it is too restrictive (in my opinion). The conclusion is only interesting if $\varepsilon$ is small, but this requires $p_k$ to be large. However, for $p_k$ large and $\varepsilon$ small, the initial condition fails. This is because the product in the condition is asymptotically $0.5614... p_k$. See my "Added" section. $\endgroup$
    – GH from MO
    Commented Feb 9, 2018 at 17:08
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    $\begingroup$ @user1582006: Whether a result is interesting enough to publish or not, is an opinion. Mathematics is a social game, not just pure science. Interesting new proofs of classical results do appear from time to time, in journals like the Amer. Math. Monthly. If your proof is really simpler than that of Erdős, then it might be worthwhile to try such a journal. $\endgroup$
    – GH from MO
    Commented Feb 9, 2018 at 17:52

1 Answer 1

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The terms in your sum tend to $1$, therefore your sum is asymptotically $k$ (as $k$ tends to infinity), which is $o(p_k)$. Hence your initial condition holds for $k$ sufficiently large, even if you replace $(1+\varepsilon)/e$ by any positive constant (e.g. by $1/100$).

It is also-well known that for given $\varepsilon>0$ and for $n$ sufficiently large (in terms of $\varepsilon$), there is always a prime number between $n$ and $(1+\varepsilon)n$. In fact it is known that, for $n$ sufficently large, there is always a prime number between $n$ and $n+n^{0.525}$.

Added. The OP changed the initial condition from $\sum_{p \le p_k} p^{\frac{1}{p-1}} \lt \frac{1 + ε}{e} p_k$ to $\prod_{p \le p_k} p^{\frac{1}{p-1}} \lt \frac{1 + ε}{e} p_k$. The new condition is false for $\epsilon=1/2$ and $k$ sufficiently large. Indeed, we have $$\prod_{p \le p_k} p^{\frac{1}{p-1}}=\exp\left(\sum_{p \le p_k}\frac{\log p}{p-1}\right)=\exp\left(o(1)+\sum_{n \le p_k}\frac{\Lambda(n)}{n}\right).$$ The right hand side is asymptotically $e^{-\gamma}p_k$, where $\gamma$ is Euler's constant, so the left hand side exceeds $\frac{1.5}{e}p_k$ for $k$ sufficiently large.

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    $\begingroup$ It's a well-known easy consequence of the Prime Number Theorem. $\endgroup$ Commented Feb 9, 2018 at 16:00
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    $\begingroup$ @user1582006: $\varepsilon$ is arbitrary, and $n$ has to be sufficiently large in terms of it. How large $n$ has to be is a different question: there are versions of the prime number theorem with good explicit error terms, which can be used for that purpose. See, for example, iml.univ-mrs.fr/~ramare/TME-EMT/Articles/Art01.html $\endgroup$
    – GH from MO
    Commented Feb 9, 2018 at 16:14
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    $\begingroup$ @GHfromMO Please reread my question. There was an error. $\endgroup$ Commented Feb 9, 2018 at 16:27
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    $\begingroup$ @user1582006 Your claim is "for every $n>p$ something happens". That includes the possibility that $n$ not be a prime. $\endgroup$ Commented Feb 9, 2018 at 16:31
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    $\begingroup$ Meanwhile, yes, "Bertrand's Postulate" was already proved 100+ years ago by Chebyshev, with a much more elementary proof than any known for the Prime Number Theorem (the key tool is the formula for the prime factorization of $x!$). $\endgroup$ Commented Feb 9, 2018 at 17:14

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