This is part 1 of a series explaining what is Harmonic number and it's connection with Zeta functions. The post …

Update 2020-04-13: A friend pointed out my comments about working at home is wrong. Most people who can do work from home now in Sweden. My apology for being part of misinfodemic 🤦!

I have been working from home for about a month now. It is actually not very common here in Sweden where universities are still open.(👮 fake news!) Unfortunately, despite my effort, I still coughed 3 times today 🤔️. Not sure if it is just the spring or I have got Covid already.

This post is converted to Markdown from this Mathematica notebook thanks to the M2MD package by Kuba Podkalicki.

I came …

I want thank David P. Sanders and Benoît Richard for helping me go through the problems I met while writing …

This is part 4 of the stories of my vacation in summer 2017 around west coast of Sweden.

In many way, this was a memorable day in my life. Yet it took me nearly 3 years to finally spend 30 minutes to write something about it. Life is not short. It's just we find excuses not to do things.

In this time of Covid-19 pandemic, many seminars have been moved to online. Here are some that I know of …

I just finished teaching the course Several Variable Calculus 1MA017 (Autumn 2019) at Uppsala University. Here are the materials that …

My colleagues at Uppsala University regularly give some puzzles to everyone. We got the following one for this week. I …