Jean-Sébastien
Reputation
3,718
Top tag
Next privilege 5,000 Rep.
Approve tag wiki edits
1 8 33
Impact
~137k people reached

# 873 Actions

 May 2 comment Calculating this integral: $I=\int_{0}^{\infty}(\log t)\,(\tan^2t)\,\mathrm{d}t$ You have bounds $0$ and $\infty$ in the title but some other numbers in the body, which is it? Apr 11 revised Minimum number of combinations added 974 characters in body Apr 11 answered Minimum number of combinations Apr 10 comment Help with this combinatorial proof $\sum\limits_{k=1}^nk^2(k-1){n\choose k}^2 = n^2(n-1){2n-3\choose n-2}$ considering $n\ge2$ Where did you get this formula? left-hand side gives $480$ and right hand side gives $160$ for $n=4$... Apr 10 comment What does this equal? $6\div 2(1+2)$ how does someone get $7$? Apr 10 reviewed Approve Sudoku candidate probability Apr 10 comment Are the two integrals equivalent? Yes they are indeed the same Apr 9 reviewed Edit Is my second equation right? Apr 9 revised Is my second equation right? Use Mathjax Apr 9 reviewed Approve How to use the Maclaurin Series to get $f^{10}(0)$ of $f(x)=(\cos(3x^2)−1)/x^2$ Apr 9 revised Convert from base 10 to base 5 improved formatting Apr 9 awarded Enlightened Apr 9 awarded Nice Answer Apr 8 revised Convert from base 10 to base 5 added 142 characters in body Apr 8 answered Convert from base 10 to base 5 Apr 5 answered What is the probability that you will see an odd number of heads? Apr 1 answered What is the legality of the following series? Mar 31 comment $f(x)=x$ if $x$ is rational , $f(x)=1-x$ if $x$ is irrational, at what point this function is continuous? You beat me to it, +1 Feb 26 comment Finding out the coeffcient next to $x^2$ in $(\cdots(x-2)^2-2)^2\cdots-2)^2$. I don't know why it is, but it seems the recurrence is $a(n)=20a(n-1)-64a(n-2)$, which gives the solution $(4*16^n-4^n)/3.$ Feb 19 comment Prove that $\sum_i\sum_j a_{ij}=\sum_j\sum_i a_{ij}$