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6 votes

Can one show that $(-1)^{n-1} {(1/\zeta)}^{(n)}(x) >0$ for all real $x>1$?

Here is a more pedestrian version of Fedor Petrov's argument: We set $\lambda=1/\log6$ and claim that $(-1)^n(1/\zeta)^{(n)}(\lambda n)>0$ if $n$ is big enough. With $a_k=\log k/k^\lambda$, we have ...
Peter Mueller's user avatar
12 votes
Accepted

Can one show that $(-1)^{n-1} {(1/\zeta)}^{(n)}(x) >0$ for all real $x>1$?

In other words, you ask whether the function $f(x):=1-1/\zeta(1+x)$ is completely monotonic on $[0,+\infty)$. We have $f(x)=\sum_{n>1} -\mu(n)/n^{1+x}=\int e^{-xt}d\lambda(t)$, where $\lambda=\sum_{...
Fedor Petrov's user avatar
3 votes

Bounds of zeta function near $\Re(s)=1$

In addition to GH from MO's answer, if one wishes to keep the $(\log|\Im(s)|)^{2/3}$ factor, then there is a very recent improvement due to Bellotti [1]. In particular, Bellotti proved that $$ \zeta(s)...
Daniel Johnston's user avatar
4 votes
Accepted

Bounds of zeta function near $\Re(s)=1$

Heath-Brown (2016) proved that, for any $\varepsilon>0$, $$\zeta(\sigma+it)\ll_\varepsilon t^{\frac{1}{2}(1-\sigma)^{3/2}+\varepsilon},\qquad 0\leq\sigma\leq 1,\qquad t\geq 1.$$ The exponent $1/2$ ...
GH from MO's user avatar
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5 votes
Accepted

Conjectured error term when counting square-free integers

Your guess is correct! It is indeed conjectured that $a=1/4$. A good recent reference is [1]. In particular, it is known that $$E(x)=\Omega(x^{1/4})$$ and computations have shown $$|E(x)|<1.12543x^{...
Daniel Johnston's user avatar
1 vote

Asymptotic behavior of weighted sums involving the fractional part function

Not an answer but a conjectural answer for the value of $C(m)$ supported by extensive numerical evidence: $$C(m)=\dfrac{1}{m-1}\sum_{2\le k\le m-1}\binom{m-1}{k}\zeta(k)+\sum_{2\le k\le m-2}\dfrac{1}{...
Henri Cohen's user avatar
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