In its convergence range, we have that the function $f(x)$ has a Taylor series shown .  What is $f(x)$ itself?  Here is the Taylor series at $x=0$ for the function:  $$ f(x)=\sum_{n=2}^{\infty} \dfrac{x^n}{n(n-1)} $$  I'm not sure about the $1$ in $n-1$.
What is the function represented by the power series $$ \sum_{k=2}^\infty\frac{x^k}{k(k-1)}\quad? $$  It looks like $\dfrac1{1-x}$ but I don't know.
Using expect to pass a password to ssh Is the external micro SD card path the same for all devices? I am using a Samsung Tab 2.  There is a path: /mnt/external_sdcard/myfile. Here, I can save, read, or write my file to the external micro SD card.  I'm just wondering if this path is the same for all devices, or if it may be different. Why exactly do sometimes universal covers, and sometimes central extensions feature in the application of a symmetry group to quantum physics? There seem to be two different things one must consider when representing a symmetry group in quantum mechanics:   The universal cover: For instance, when representing the rotation group $\mathrm{SO}(3)$, it turns out that one must allow also $\mathrm{SU}(2)$ representations, since the negative sign a "$2\pi$ rotation" induces in $\mathrm{SU}(2)$ is an overall phase that doesn't change the physics. Equivalently, all representations of the Lie algebra are what we seek. ($\mathfrak{so}(3) = \mathfrak{su}(2)$, but although every representation of the algebra is one of the universal cover, not every representation of the algebra is one of $\mathrm{SO}(3)$.) Central extensions: In conformal field theory, one has classically the  of infinitesimal conformal transformations. From the universal cover treatment one is used to in most other cases, one would expect nothing changes in the quantum case, since we are already seeking only representation of an algebra. Nevertheless, in the quantization process, a  appears, which is often interpreted to arise as an "ordering constant" for the now no longer commuting fields, and we have to consider the  instead.   The question is: What is going on here? Is there a way to explain both the appearence of universal covers and central extensions in a unified way? Given a hotkey, how can I find which program owns it? Since Newton's law of gravitation can be gotten out of Einstein's field equatons as an approximation, I was wondering whether the same applies for the electromagnetic force being the exchange of photons. Is there an equation governing the force from the exchange of photons? Are there any links which would show how the Coulomb force comes out of the equations for photon exchange? I know that my question is somewhat similar to the one posted here , but it doesn't really have an answer to my question specifically. Product of invertibles in $\Bbb Z_n$ [Wilson's Theorem generalization] How can we compute the product of all invertibles in $\Bbb Z_n$?  In the special case $n=p$ where $p$ is a prime it is Wilson's theorem. By pairing inverses it reduces to computing the product of all $a$ such that $a^2\equiv 1\pmod{n}.\,$  How can we do that? When I tried to connect my Ubuntu 13.10 to my VM Centos 6.5 using ssh appear the message "Connection refused" or "No route to host" even than I change the port, noting change.    I need to use SSH, VPN and Samba, but this IP in my VM Centos do not work.  How Can I resolve this problem? I am trying to modify output in my twig file. In D7, I was able modify data in my array with this  check_markup($tweet-&gt;text, 'full_html');   and I see that this function still exists in D8. However, I'm not sure how I would use this in a filter in twig. This is what I have so far:  {% for tweet in params.tweets %} &lt;div class="tweet-wrapper"&gt; &lt;div class="tweet-profile-image"&gt;     &lt;img src='{{ tweet.user.profile_image_url }}'/&gt; &lt;/div&gt; &lt;div class='tweet-text'&gt;     &lt;!--check_markup($tweet-&gt;text, 'full_html');--&gt;     {{ tweet.text }} &lt;/div&gt;   &lt;/div&gt; {% endfor %}   I actually tried to do this before I sent it to the template as well, but it didn't change anything:   foreach($tweets as $tweet) {   $tweet-&gt;text = check_markup($tweet-&gt;text, 'full_html');   $cleanTweets[] = $tweet; } dpm($tweets); $params = array('tweets' =&gt; $cleanTweets); $tweet_template = array('#theme' =&gt; 'twitter_pull_tweet_listing', '#params' =&gt; $params); return $tweet_template;   What I'm trying to do here is make drupal create links for web links in the twitter tweet text. This worked fine for me in D7. What is the proper way of creating installation media from Ubuntu iso? Boolean and Texts I have used Hexagon for years but find that it sometimes crashes when trying to do Boolean operations with texts.  I have been trying to make the two tables of the Ten Commandments and have been trying to use Blender.  I did it about two years ago in Blender and lost everything on my computer so I am trying again with the latest version of Blender and am having difficulty.  I start with a cube and then get it close to the dimensions I would think the Ten Commandments might look like. I then bevel the top using the bevel modifier. But in doing it this way I don't have any cross sub divisions on the face of the object. I have tried sub dividing first but then I find that I can't bevel the top arches as far as I would like. I still don't know how to add divisions after I bevel the top. Yes I am still a novice at this program.  In any case I did figure out how to make text and turn them into an object. When I make the texts I do all four of the commandments for one side and then the other six for the other side. So this makes allot of texts to cut out.  When doing the Boolean operation in Difference sometimes nothing happens. I am thinking I need to have some sub - divisions on the face of the sized cube after it is beveled but am not really sure if this is the problem.  This whole thing about normal's is still Greek to me. I have watched some videos on how to cut letters into a cube but for some reason it does not work this easy after I bevel the top of the cube. Or it could be that Blender does not like a bunch of texts all at once.  Could someone show me a video or give me some simple steps to make my project work? Simple extension fields If I am correct simple extension fields are extensions generated by one element. I have learned that this means that elements of a simple extension can be written as powers of that element as long as the power is greater than the degree of that element. Also this means that all elements of the simple ext. Can be written in terms of decending powers of the generating element where the highest power is the degree of the generator minus 1. This concept seems to work for generating elements whose irreductable in a certain field is a descending degree polynomial. Looking at the construction of the complex numbers by starting with $\Bbb R$ (and doing $\Bbb R [x]/\langle x^2+1\rangle$), it is said that all elements are of the form $a+b\cdot \text{generator}$. But when the generator is evaluated for the irreductable, $x^2+1$, we see... $(\text{generator})^2=-1$. Thus there is no first power of gen. Can someone explain where all elements of the extension just explained are of the form $a+b\cdot \text{generator}$ comes from or explain this situation for anytime where the irreduc ( gen, F)  is not a descending degree polynomial. I hope my question is clear.  Thank you To be honest I find it hard to keep up with all the changes, and very frequently I have to go look at the privileges list to see whether a user (that I'm looking at, so I have his reputation value) has a certain privilege or not.  However, I still don't know what that user will actually see or how the site actually behaves for that user.  There's quite a number of posts here on meta about "where did this go" and "why can't I" and I can't really tell either way how a site behaves for a user with a reputation level of 2500.  So, I propose the following functionality:   For all users, be able to view the site as though you had less reputation than you actually have Bonus-feature: For all users, be able to use the site at that reputation level, unless some features of low-level users conflict with your actual functionality For mods, be able to view the site as a specific users (be able to see all he sees, exactly the way he sees it), but of course not pose as that user (ie. things I do would still be me)   The UI could be merged into the mod menu and the privileges menu:    (Note, I chose a user randomly, Olivier Pons is in no way related to this question or flags, or whatever that I know of.) I don't do math a long time, so I completely don't remember how to prove that: $$ \sum_{i=1}^\infty \frac{i}{2^i} = 2 $$  Can anybody help me? I need to do a polynomial interpolation of a set $N$ of experimental points; the functional form I have to use to interpolate is this:  $$ f(x) = a + bx^2 + cx^4,$$ as you can see the coefficient that I need to find are just 3: $a, b, c$; however the points I have are $\#N&gt;3$ and so it looks like the determination of the coefficients is impossible because is over-determined. Does anyone have an idea of what should be done in such case (supposing it is even possible)? How can I block app and game invitations once and for all in Facebook? I want to block app and game invitations once and for all in Facebook. How can I do it so they cannot disturb me anymore? How do you uninstall wine 1.5? What is the command to open the shutdown dialog? How do the likely/unlikely macros in the Linux kernel work and what is their benefit? How many String objects will be created when using a plus sign? How to group distinct values from a list using odata rest api Hi I have a list with two fields "Regions" &amp; "Countries" I am using a rest api to retrieve the list of just regions like so: http:mysitename/_api/web/lists/getByTitle('TaxTool')/items?$select=Region  In the results there are lots of duplicates and I was wondering how to return unique values.