During its travels the problem has been christened with a variety of names.
Collatz's colleague H. Hasse was interested in the problem and
discussed generalizations of it with many people, leading to the name
Hasse's algorithm .
The name Syracuse problem was proposed by Hasse during a visit to
Syracuse University in the 1950's.
Around 1960, S. Kakutani heard the problem, became interested in it,
and circulated it to a number of people.
He said ``For about a month everybody at Yale worked on it,
with no result.
A similar phenomenon happened when I mentioned it at the University of Chicago.
A joke was made that this problem was part of a conspiracy to slow down
mathematical research in the U.S. .''
In this process it acquired the name Kakutani's problem.
S. Ulam also heard the problem and circulated the problem at
Los Alamos and elsewhere, and it is called Ulam's problem
in some circles (, ).