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The Collatz Conjecture, also known as the 3n+1 conjecture, is a famous open problem named after Lothar Collatz.

47 votes
1 answer
2k views

Transitivity on $\mathbb{N}_0$ -- a 42 problem

Let $r(m)$ denote the residue class $r+m\mathbb{Z}$, where $0 \leq r < m$. Given disjoint residue classes $r_1(m_1)$ and $r_2(m_2)$, let the class transposition $\tau_{r_1(m_1),r_2(m_2)}$ be the permu …
Stefan Kohl's user avatar
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3 votes
0 answers
174 views

Largest permutation groups without "non-mixing" subgroups

We say that a subgroup of ${\rm Sym}(\mathbb{N})$ has sparse orbit representatives if it has infinitely many orbits on $\mathbb{N}$, but the set of smallest orbit representatives has natural density 0 …
Stefan Kohl's user avatar
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1 vote
1 answer
239 views

Group with 2 orbits on the nonnegative integers -- description of the orbits

Definition: Let $r(m)$ denote the residue class $r+m\mathbb{Z}$, where $0 \leq r < m$. Given disjoint residue classes $r_1(m_1)$ and $r_2(m_2)$, let the class transposition $\tau_{r_1(m_1),r_2(m_2)}$ …
Stefan Kohl's user avatar
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11 votes
Accepted

Collatz stopping-time and Poisson distribution, and connection to other problems?

As to the observed distribution of total stopping times for integers $n \leq 10^8$, I think heuristically this can be explained quite well by the obvious stochastic model (multiply $n$ by $3/2$ or $1/ …
Stefan Kohl's user avatar
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