# Who is the Göbel who is the eponym of Göbel's Sequence?

Richard K. Guy refers to him as "F. Göbel" in his Unsolved Problems of Number Theory but that's as close as I can get.

For reference:

https://mathworld.wolfram.com/GoebelsSequence.html

• Nothing at Mactutor. – Spencer Nov 5 '20 at 15:29
• Göbel also appears to have been quite active in recreational mathematics as the designer of mathematical puzzles and contributor to the Dutch recreational mathematics journal The Dutch Cubist Club. – Nick Nov 5 '20 at 18:46
• For a number of years, Frits Göbel was also responsible for a column on recreational mathematics in the journal Euclides which is the main publication of the Dutch association of math teachers (Nederlandse Vereniging van Wiskundeleraren) from what I can gather. – njuffa Nov 6 '20 at 0:07
• Dr. Frits Göbel was part of the Faculty of Applied Mathematics at the University of Twente until 1998. – njuffa Nov 6 '20 at 0:58

Then I tried the google search "Göbel's sequence" + "Fritz" and got exactly one hit, this 25 September 1986 letter from Richard K. Guy to Neil J. A. Sloan. The sequence $$1,$$ $$2,$$ $$3,$$ $$5,$$ $$10,$$ $$28,$$ $$154,$$ $$3520,\, \ldots$$ at the bottom of the first page is identified with the name Fritz Göbel. The google search "Fritz Göbel" + "sequence" appears to confirm that this is the Göbel you want. I don't know whether he has a middle name or his birth year, but I believe he is still alive.