3X+1 cycles having length k=⌈i log_2(3)⌉

26 February 2026, Version 1
This content is an early or alternative research output and has not been peer-reviewed by Cambridge University Press at the time of posting.

Abstract

A "3x+1" cycle of length k occurs when the Collatz function T(n), which takes odd integers n to (3n+1)/2 and even integers n to n/2, applied to an initial integer a0, reach that initial value again after k iterations, so that T^(k)(a0)= a0. It is conjectured that any cycle must have k=⌈i log_2(3)⌉ where i is the number of odd elements in the cycle. It is easy to show that in cycles where a0 is the smallest integer, i<3a0 implies k=⌈i log_2(3)⌉. This paper will show that in cycles, i<304a0 implies k=⌈i log_2(3)⌉. In m-cycles m<1.8296017a0 implies k=⌈i log_2(3)⌉.

Keywords

Collatz
cycle
11B83
length

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