Do F-1 students need a visa to visit Paris and Amsterdam during layovers?
Do I need a visa to transit (or layover) in the Schengen area?
How to calculate the limit of $\frac{a_n}{n^2}$ for the sequence $a_{n+1}=a_n+\frac{2 a_{n-1}}{n+1}$? Assume $\{a_n\}$is a sequence which  satisfies the following recursion formula: $$a_{n+1}=a_n+\frac{2a_{n-1}}{n+1}~(n\geqslant 1).$$ and $a_0=\pi,a_1=\pi^2 $. How to compute $\displaystyle\lim_{n\to \infty}\frac{a_n}{n^2}$? My tweets are not showing up in other people's mentions My replies are not showing up in other people's mentions. I tried tweeting several friends, my other accounts but my tweets just won't appear in their mentions? They do appear on my own Twitter page. It's been almost 24 hours now and it's pretty frustrating. How to solve differential equations of the form $f'(x) = f(x + a)$ What could one do to find analytic solutions for $f'(x) = f(x + a)$ for various values of $a$?  I know that $c_1\sin(x + c_2)$ is solution when $a = \frac{1}{2}\pi$, and of course $c_1e^x$ when $a = 0$.  For instance, is there a function satisfying $f'(x) = f(x + 1)$?  What about negative or imaginary $a$?  Is there possibly a generalization? Where Android apps store data? I'm having an issue with blender where whenever I try to render as any sort of video, instead of showing up as an mp4 or whatever file type I chose, it will show up as a mystery file that cannot be opened. This issue started recently and randomly: I was always able to render perfectly fine before and I used the exact same settings now that I did then.   not sure exactly what I'm doing wrong. Here are the export settings I am using: pgfplots: lines and markers in different colors With pgfplots, I am creating a simple coordinate plot with error bars like this:    \documentclass[crop,10pt]{standalone} \usepackage[english]{babel} \usepackage{pgfplots}      \begin{document}%         \setlength{\linewidth}{246pt}%              \begin{tikzpicture}             \begin{axis}[             width=\linewidth,             ytick pos = left,             xtick pos = left,             clip=false,             axis on top,             tick align = outside,             yticklabel style={%             /pgf/number format/fixed,             /pgf/number format/precision=1,             /pgf/number format/fixed zerofill         },             ytick scale label code/.code={},             xlabel={X},             ylabel={Y},     ]             \addplot[mark=*]             plot[             error bars/.cd,             y dir=both,             y fixed=0.0001     ]             coordinates{(1,0.0005) (1.1,0.0013) (5,0.0015)};             \end{axis}             \end{tikzpicture}     \end{document}   In the original plot I have a lot more points. I would now like the line and the markers (including the error bars) to have different colors to better distinguish the line from the error bars. Is that somehow possible? The only way I found so far is to plot the data just as a line in one color and then plot it again just as markers in another color. This works, but I guess there must be some better solution to this. Thanks for the support, John For example:  $ sudo apt-get install curl Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies: bsh : Depends: libjline-java but it is not going to be installed groovy : Depends: libjline-java but it is not going to be installed rhino : Depends: libjline-java but it is not going to be installed E: Unmet dependencies.   Try 'apt-get -f install' with no packages (or specify a solution).   I get the same or similar errors when I attempt to install clojure1.3, leiningen, and several other packages.   When I try the suggestion made in the error message, this is what happens:  $ sudo apt-get -f install  Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... Done The following packages were automatically installed and are no longer required:   diffstat linux-headers-3.2.0-26-generic linux-headers-3.2.0-26 dh-apparmor dkms html2text libmail-sendmail-perl libsys-hostname-long-perl Use 'apt-get autoremove' to remove them. The following extra packages will be installed:   libjline-java Suggested packages:   libjline-java-doc The following NEW packages will be installed:   libjline-java 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. 23 not fully installed or removed. Need to get 0 B/72.0 kB of archives. After this operation, 129 kB of additional disk space will be used. Do you want to continue [Y/n]? Y (Reading database ... 226243 files and directories currently installed.) Unpacking libjline-java (from .../libjline-java_1.0-1_all.deb) ... dpkg: error processing /var/cache/apt/archives/libjline-java_1.0-1_all.deb (--unpack):  trying to overwrite '/usr/share/java/jline.jar', which is also in package scala 2.9.2-400 Errors were encountered while processing:  /var/cache/apt/archives/libjline-java_1.0-1_all.deb E: Sub-process /usr/bin/dpkg returned an error code (1)  $ sudo apt-get upgrade Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies:  bsh : Depends: libjline-java but it is not installed  groovy : Depends: libjline-java but it is not installed  rhino : Depends: libjline-java but it is not installed E: Unmet dependencies. Try using -f. Show for prime numbers of the form $p=4n+1$,  $x=(2n)!$ solves the congruence $x^2\equiv-1 \pmod p$. $p$ is therefore not a gaussian prime. I've got a custom loop that I'm using to display some Real Estate listings that will be available within 60 days. I'm calling it with the following function:   &lt;?php  $sixtydays = date('Y/m/d', strtotime('+60 days')); $paged = (get_query_var('paged')) ? get_query_var('paged') : 1; $query = new PostsOrderedByMetaQuery(array(   'post_type' =&gt; array('post', 'real-estate'),   'meta_key' =&gt; 'Time Available',   'meta_compare' =&gt; '&lt;=',   'meta_value' =&gt; $sixtydays,   'paged' =&gt; $paged,   'orderby_meta_key' =&gt; 'Price',   'orderby_order'    =&gt; 'ASC' )); ?&gt; &lt;?php while ($query-&gt;have_posts()) : $query-&gt;the_post(); ?&gt;   While the loop works great, I can't get it to paginate. It shows the first 10 (my default) posts but doesn't show the pagination. The only way to display all posts is to show them on one page by adding 'posts_per_page' =&gt; -1, I have similar loops on other pages that have no problem paginating. The only difference with this one is that there are two meta keys that are filtering the posts.   I'm using WP Page Navi for this and the rest of my pages. I'm closing the loop and adding the pagination using the following code:   &lt;?php endwhile; // End the loop. Whew. ?&gt; &lt;?php wp_pagenavi(); ?&gt; &lt;?php wp_reset_query(); ?&gt;   How can I go about fixing this? Allow folding/collapsing of certain segments of posts A question with attachments, screenshots and/or long code, makes it vertically long and often difficult to read fast.  It would be nice to have a new kind of format, such as 'hideable', with a graphic button or a '+' / '-' sign, so you can add additional details, visible only on a click. How can I filter items with a certain enchantement? How closely can a game legally resemble another? Product of quotient maps and quotient space that is not Hausdorff I am looking for easy(!) counterexamples that the product of two quotient maps is not necessarily a quotient map and that the quotient space of a Hausdorff space is not necessarily Hausdorff. Is there a criterion to differentiate "thriller" from "horror"? Putting a piece of code in between two html tags in Solaris How can I change PulseAudio port priorities? I list sources and sinks as follows:  pactl list sources pactl list sinks   The output I get is:  ...     Ports:         analog-input-internal-mic: Internal Microphone (priority: 8900)         analog-input-headphone-mic: Microphone (priority: 8700)         analog-input-headset-mic: Headset Microphone (priority: 8800) ...     Ports:         analog-output-speaker: Speakers (priority: 10000)         analog-output-headphones: Headphones (priority: 9000, available)    How do I change the priorities listed above and have them fixed at what I change them to? Note that I am not looking to set a default source and sink or to delete unwanted sources or sinks, I just want to be able to assign them different priorities. Call blocking for iPhone? How do I block unwanted callers without jailbreaking? Feature selection with Random Forests biblatex and autonum don't work together Potential difference across a zero resistance wire So I started off with electrostatics and everything seemed nice and mathematical and justified and then "DC circuits" happened!  I just cannot understand the model of electron flow in electrical circuits.  Here are my specific doubts-:  1) If potential difference across a tiny cross section of conducting wire is zero, then why on earth does electron flow across that cross section at all? Never mind potential difference across the whole circuit.   2) Is there a constant electric field across a wire connected to a battery? If yes then how is potential difference across a zero resistance wire constant?   Shouldnt it be increasing?  Doesnt it violate ohms law?  If no,  then why do electrons flow at all?  Please take time to consider these doubts and relieve me of my frustration.  I havs searched through the net for this but every answer seems like beating around the bush.  All of the 4 books I have consulted do not address these facts to my satisfaction.   Frankly I think nobody understands this.