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Every Odd Number Greater Than 1 is the Sum of at Most 241 Primes

Proved
odd_sum_le_241_primes

by xuanji · Oct 4, 2026 · Mathlib 0df444a (Lean v4.33.1)

goldbachnumber-theoryschnirelmann-densitysieve-theory

Every odd natural number greater than 111 is a sum of at most 241241241 primes, with repetition allowed.

Precisely: for every n∈Nn \in \mathbb{N}n∈N with nnn odd and n>1n > 1n>1 there is a finite multiset sss of natural numbers such that

∣s∣≤241,every p∈s is prime,∑p∈sp=n.|s| \le 241, \qquad \text{every } p \in s \text{ is prime}, \qquad \sum_{p \in s} p = n.∣s∣≤241,every p∈s is prime,p∈s∑​p=n.

Here ∣s∣|s|∣s∣ counts elements with multiplicity, so the same prime may be used several times, and the order of the summands is irrelevant.

This is the campaign statement of Odd numbers as sums of primes with the value 241241241.

Formalization Note The representation is a Multiset ℕ; the bound is on Multiset.card, so repeated primes count separately.

Preamble
import Mathlib
Formal statement
theorem odd_sum_le_241_primes (n : ℕ) (hodd : Odd n) (hn : 1 < n) :
    ∃ s : Multiset ℕ, s.card ≤ 241 ∧ (∀ p ∈ s, Nat.Prime p) ∧ s.sum = n := by
  sorry
Source
AI-assisted explicit calculation (unpublished, October 2026), improving the K = 100001 note: sigma(A) >= 1/120 via a weighted sixteenth-moment / Hölder argument, then Mann's theorem gives 240B = N, K = 241; framework: P. Pollack, Not Always Buried Deep, Ch. 6 §6 (incl. Mann's theorem), https://www.pollack-math.net/NABDofficial.pdf
Read-back

What the Lean code literally says, in plain math · claude-opus-5-5

Read-back: odd_sum_le_241_primes

For every natural number nnn such that

  • nnn is odd, meaning n=2k+1n = 2k+1n=2k+1 for some natural number kkk, and
  • n>1n > 1n>1 (strictly),

there is a finite multiset sss of natural numbers with these three properties:

∣s∣≤241,every element p∈s is prime,∑p∈sp=n.|s| \le 241, \qquad \text{every element } p \in s \text{ is prime}, \qquad \sum_{p \in s} p = n .∣s∣≤241,every element p∈s is prime,p∈s∑​p=n.

In other words, every odd natural number nnn greater than 111 can be written as the sum of at most 241241241 primes. Here "prime" is the usual notion for natural numbers: p≥2p \ge 2p≥2 and the only divisors of ppp are 111 and ppp.

Fine print:

  • Since sss is a multiset, the same prime may appear more than once, and ∣s∣|s|∣s∣ counts every copy.
  • The order of the summands does not matter.
  • The bound is the non-strict ≤241\le 241≤241, so any number of summands from 111 to 241241241 is allowed. For example, when nnn is itself prime, the one-element multiset {n}\{n\}{n} works.
  • The empty multiset (zero summands, sum 000) can never be a witness, because n≥3n \ge 3n≥3.
  • Together the two hypotheses say exactly that nnn ranges over 3,5,7,9,…3, 5, 7, 9, \dots3,5,7,9,…. They can always be satisfied, so the statement is not vacuous.
  • The statement only claims that such a multiset exists. It says nothing about the summands being distinct, about how many representations there are, or about any bound smaller than 241241241.
  • No other variables, assumptions or definitions appear. The statement uses only the standard library notions of oddness, primality, multiset size and multiset sum.
Human review
  • Endorsed by Shuze Chen · Oct 5, 2026

    Confirmed by the moderator at approval.

  • Endorsed by xuanji · Oct 5, 2026

    Confirmed by the mission captain (proposal self-audit).

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