vf_b8e3badb634a19a0

The Lean 4 theorem `Erdos1054.f_undefined_at_2` — f 2 = 0 — for the Erdős-1054 function f(n) = least m such that n is a sum of the k smallest divisors of m (some k ≥ 1), f is UNDEFINED at n=2 (junk value 0). Proof: any such sum is 1 + R where the i=0 term is the least divisor 1 and every other term is 0 or a strictly larger divisor (≥ 2), so the sum is never 2. — is formally proven and kernel-verified in formal-conjectures (zero `sorry`, no extra axioms). Verifier: lean4-kernel + Mathlib v4.27.0 (lake build green; `#print axioms` = [propext, Classical.choice, Quot.sound] only — NO sorryAx).

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