Coin Loops (noch nicht übersetzt)
A game is played with many identical, round coins on a flat table.
Consider a line perpendicular to the table.
The first coin is placed on the table touching the line.
Then, one by one, the coins are placed horizontally on top of the previous coin and touching the line.
The complete stack of coins must be balanced after every placement.
The diagram below [not to scale] shows a possible placement of 8 coins where point P represents the line.

It is found that a minimum of 31 coins are needed to form a coin loop around the line, i.e. if in the projection of the coins on the table the centre of the nth coin is rotated θn, about the line, from the centre of the (n−1)th coin then the sum of n∑k=2θk is first larger than 360∘ when n=31. In general, to loop k times, n is the smallest number for which the sum is greater than 360∘k.
Also, 154 coins are needed to loop two times around the line, and 6947 coins to loop ten times.
Calculate the number of coins needed to loop 2020 times around the line.