My biggest thanks goes to my mathematics teacher Franz Hagen (PhD), who accompanied me at the high school (Gymnasium) in Oer-Erkenschwick from 9th to 13th grade (Abitur). He was the one who taught me the joy of mathematics and recognized something like a talent. I dedicate this internet presence to him.

I thank the many mathematicians around the world who were kind enough to answer my questions, to critique my texts and ideas, or to help me in any other way. I would like to mention the following persons in alphabetical order.

Friedrich Ludwig Bauer
Christian Boyer
Jonathan Borwein
Holger Dette
Peter Dinkelacker
Andreas Fillipi
Erich Friedman
Dirk Frettlöh

Heiko Harborth
Michael Joswig
Bernhard Klaaßen
Sascha Kurz
Jeffrey C. Lagarias
Lee Morgenstern
Tony D. Noe
Christoph P. Pöppe

Harald Scheid
David Sixsmith
Neil J. A. Sloane
Alexander Soifer
Stefan Vogel
Hans Walser
Günther Wirsching
Dieter Wolke