Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options answers only not deleted user 498835

Asymptotic behavior of functions, asymptotic series and related topics

46 votes
Accepted

A challenging (for me) limit calculation

This limit converges to $\frac{\sqrt3}2$. The idea is that $\sin(x) = x - \frac{x^3}6 + O(x^5)$, so we start with $\frac1{\sqrt n}$ and repeatedly subtract $\frac{x^3}6$. We can approximate this discr …
Daniel Weber's user avatar
  • 3,319
8 votes
Accepted

Series with the smallest number whose square is divisible by $n$

I couldn't find a reference, but (as noted in the OEIS page) if we have $k = a b^2$ with squarefree $a$ then $a(k) = ab$, so $$\begin{align*} \sum_{k\leq x}\frac1{a(k)} &= \sum_{a b^2 \leq x} \frac{\m …
Daniel Weber's user avatar
  • 3,319
0 votes

Expected sorting time of random permutation using random comparators

Here's a proof that $\mathbf{E}[X] = O(n^2 \log^2(n))$. Let's assume WLOG $n$ is a power of 2. Let's calculated the expected time until all values bigger than $\frac{n}2$ are in the second half (and a …
Daniel Weber's user avatar
  • 3,319