Althöfer · Does the 9n+1 orbit from 1 diverge?

Prove or disprove that the 9n+1 trajectory starting from 1 tends to infinity.

Collatz variantsinteger iterationdiscrete dynamics

The problem

Prove or disprove that the 9n+1 trajectory starting from 1 tends to infinity.

Open sinceUnknowndate not stated

Last checked2026.07.27Catalog verification

Offer 01€50Ingo Althöfer

Personal offer

First solution wins; computer-assisted proofs are allowed, the sponsor excludes legal recourse, and the offer expires on 31 December 2037.

Published deadline: 2037-12-31