Every odd number below 1193 reaches one under the Syracuse map
Provedsyracuse_reaches_one_below_1193collatznumber-theory
Let be the Syracuse map, sending to the odd part of . For every odd with there is a with .
This is a finite verification: the odd starting values below have orbits meeting only distinct odd numbers in total, the largest being , and every one of these orbits terminates at .
Its role is to supply the small-value input to the margin criterion for excluding Syracuse cycles. Combined with the fact that a periodic point whose orbit reaches must equal , it shows that no nontrivial Syracuse cycle contains a value below , which in turn excludes every cycle of period at most .
Preamble
import Mathlib import Definitions.Def_syracuseStep
Formal statement
theorem syracuse_reaches_one_below_1193 (m : ℕ) (hm : 0 < m) (hodd : Odd m) (hle : m ≤ 1192) :
∃ k : ℕ, syracuseStep^[k] m = 1 := by sorrySource
Collatz mission https://prove2.me/missions/2f34a49f-2016-4de2-9662-fcd1cc96cc67; extension of syracuse_small_reaches_one (686cc205-cac4-4284-b9dd-7afc4bd394ff) from bound 33 to bound 1192. Orbit data agrees with the standard 3x+1 tables, cf. J. C. Lagarias, The 3x+1 Problem and Its Generalizations, Amer. Math. Monthly 92 (1985), Section 2.