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Here is a closed form of an integral that looks like:

Integral form(s) of a general tetration/power tower integral solution: $$\sum\limits_{n=0}^\infty \frac{(pn+q)^{rn+s}Γ(an+b,cn+d)}{Γ(An+B)}$$

Using this identity and the series expansion of the Lambert W function and digamma function:

$$\text W(x)\mathop=^{|x|<\frac1e}\sum_{n=1}^\infty \frac{(-n)^{n-1}x^n}{n!}=-\int_1^\infty\lfloor x\rfloor d\left( \frac{(-n)^{n-1}x^n}{n!}\right)dn=-\int_0^\infty\lfloor n\rfloor \frac{(-n)^{n-1}x^n\left(1-\frac1n +\ln(-n)+\ln(x)-ψ(n+1)\right)}{n!}dn= \int_0^\infty \frac{\lfloor n\rfloor (-n)^{n-1}x^n }{nn!}dn-(\ln(x)+1)\int_0^\infty \frac{\lfloor n\rfloor (-n)^{n-1}x^n }{n!}dn -\int_0^\infty \frac{\lfloor n\rfloor\ln(-n) (-n)^{n-1}x^n }{n!}dn+\int_0^\infty \frac{\lfloor n\rfloor ψ(n+1) (-n)^{n-1}x^n }{n!}dn $$

Here is a graph of the integrand:

enter image description here With this example when $x=\frac 13$. What are some other integrals that can be derived with the W-Lambert function with a power tower expression in the integral? One idea is to use the Abel-Plana formula on $\sum\limits_{n=1}^\infty \frac{(-n)^{n-1}x^n}{n!}$ if it works. Please correct me and give me feedback!

Тyma Gaidash
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    My impression is that you post a lot of questions seeking closed forms for various integral expressions. Why? What is the motivation? What are these closed forms good for? What are you (or anyone else) going to do with them? Are they numerically useful? Can you prove theorems with them? What is the point? The goal of Math SE is to provide a resource for everyone. If the integrals that you are studying are only of interest to you, and have no further application, then I don't think that they are a good fit for this format. You might consider starting a blog... – Xander Henderson Dec 17 '21 at 01:58
  • @XanderHenderson The integrals can be used to solve problems like those in this post which are similar. – Тyma Gaidash Dec 17 '21 at 02:08
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    You've just made my point for me---you have linked back to a previous post which you have written. So the motivation for this post is to develop techniques for solving problems you introduced in a previous post. Why should anyone in the broader mathematical community be interested in these integrals? How are these questions of general interest? – Xander Henderson Dec 17 '21 at 13:36
  • @XanderHenderson Not that there will be one, but how does a blog help? Unless one promotes it, it would be another website forgotten by the public. Even if you promoted one, it would just be pages of text for free. Thanks. – Тyma Gaidash Aug 01 '22 at 12:37
  • I don't understand your question. What do you mean "how does a blog help?" Where did I say that a blog would help? The goal of this site is to host questions and answers which have the potential to be of broad interest. The point of a blog is for an author (or authors) to share things which they, personally, find interesting. You seem to be using questions here in the same way that blog authors use their blog posts. Hence it seems like you want to write a blog, not write questions and/or answers for this site. – Xander Henderson Aug 01 '22 at 12:43
  • The point is that you seem to be attempting to use this site in a manner other than how it is intended. – Xander Henderson Aug 01 '22 at 12:43
  • That really didn't clarify my question at all. I never said that a blog would "help", hence I don't understand the question "how does a blog help?" I am making the point that you are treating Math SE like your own personal blog, hence maybe you should go start one of those, instead. – Xander Henderson Aug 01 '22 at 12:45
  • Note: The point was not actually made for the moderator, but rather the linked question has upvotes and engagement indicating it has interest. Therefore, methods, however specific, from this question can be used for the linked question for the “broader mathematical community”. – Тyma Gaidash Aug 12 '23 at 20:16
  • Why the spurious downvote? It looks like someone is following this post – Тyma Gaidash Aug 12 '23 at 22:16

1 Answers1

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I know this question is a bit repetitive, but I could not ignore writing the following result using the Abel-Plana formula because it really works. Here is the final result:

$$\text W(x)\mathop=^{|x|<\frac 1e}\sum_{n=0}^\infty \frac{(-1)^n (n+1)^n x^{n+1}}{n!}=\frac t2+ \frac {it}2\int_0^\infty \frac{(it+1)^{it}x^{it}\text{csch}(\pi x)}{(i t+1)!}dt-\frac{i t}2\int_0^\infty \frac{(1-it)^{-it}x^{-it}\text{csch}(\pi x)}{(1-i t)!}dt $$

Now try to derive some other results using this one with substitutions etc. Please correct me and give me feedback!

Тyma Gaidash
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