255 reputation
19
bio website ptspts.blogspot.com
location Zurich, Switzerland
age 33
visits member for 3 years, 10 months
seen yesterday

Programming for fun and profit. Hacking together TeX macros. Written gzip decompressor in PostScript. Writing multilingual programs, such as:

%:/*:if 0;"true" +s ||true<</;#|+q|*/include<stdio.h>/*\_/
{\if(%)}newpath/Times-Roman findfont 20 scalefont setfont(
%%)pop 72 72 moveto(Just another PostScript hacker,)show((
t)}. t:-write('Just another Prolog hacker,'),nl,halt. :-t.
:-initialization(t). end_of_file. %)pop pop showpage(-: */
int main(){return 0&printf("Just another C%s hacker,\n",1%
sizeof'2'*2+"++");}/*\fi}\csname @gobble\endcsname{\egroup
\let\LaTeX\TeX\ifx}\if00\documentclass{article}\begin{doc%
ument}\fi Just another \LaTeX\ hacker,\end{document}|if 0;
/(J.*)\$sh(.*)"/,print"$1Perl$2$/"if$_.=q # hack the lang!
/
sh=sh;test $BASH_VERSION &&sh=bash;test $POSIXLY_CORRECT&&
sh=sh;test  $ZSH_VERSION && sh=zsh;awk 'BEGIN{x="%c[A%c[K"
printf(x,27,27)}';echo "Just another $sh hacker," #)pop%*/

1d
revised Number of coprimes of $n$ divisible by 3
added 4 characters in body
2d
comment Eulers totient function divided by $n$, counting numbers in the set [1,m] that are coprime to n
Answering my question: the inclusion-exclusion principle cna be used to do the counting: math.stackexchange.com/a/1038805/5758
2d
answered Number of coprimes of $n$ divisible by 3
2d
comment Eulers totient function divided by $n$, counting numbers in the set [1,m] that are coprime to n
Is there a related theorem when $m*\omega(n)/n$ is not an integer? Where can I read more about this?
2d
revised Number of coprimes of $n$ divisible by 3
edited title
2d
comment Number of coprimes of $n$ divisible by 3
@Peter: Yes, as I wrote in my previous comment, neither $\mathrm{floor}(\varphi(3n)/3)$ nor $\mathrm{ceil}(\varphi(3n)/3)$ work.
2d
comment Number of coprimes of $n$ divisible by 3
@Peter: $\mathrm{floor}(\varphi(3n)/3)$ is incorrect for many numbers smaller 100. $\mathrm{ceil}(\varphi(3n)/3)$ is also incorrect for many numbers smaller 100. Both are incorrect for $n=110$ and many other numbers.
2d
asked Number of coprimes of $n$ divisible by 3
Oct
1
answered What is the maximum area of measurable sets on the plane with given diameter?
Oct
1
asked What is the maximum area of measurable sets on the plane with given diameter?
Mar
18
suggested suggested edit on Prove the convergence of $\lim_{n \rightarrow \infty} \frac{23^n}{n^{13}} \cdot \frac{1}{6}$
Oct
27
comment What is the simplest proof of the pythagorean theorem you know?
You also need to prove that in the figure on the right the large white area is a square. It's obvious that all its sides have the length $c$, but are the angles right angles?
Oct
2
revised Inequality…(RMO $1994$…question $8$)
moved the multiplication dot above the baseline
Oct
2
suggested suggested edit on Inequality…(RMO $1994$…question $8$)
Sep
27
awarded  Critic
Sep
26
comment Surprising identities / equations
There are not other integer solutions (except for $x=y$).
Sep
26
comment Surprising identities / equations
More explanation here: en.wikipedia.org/wiki/…
Sep
10
comment How can one prove that $e<\pi$?
Since $(1+1/n)^n<(1+1/n)^{n+1}$, it's enough to prove that the latter is decreasing. It starts from 4, then 3.375, then 3.16..., then 3.05..., then 2.98..., already smaller than 3.
May
14
awarded  Caucus
Apr
14
awarded  Nice Question