Order 11 = 11

0 / 1 paper-excluded 0 / 1 Lean-excluded odd candidate

Why a candidate

Order 11 = 11 is a candidate because it divides the following Theorem 6 maxima: 275.

From the paper (Macaj–Siran 2010)

MP 2001 Lemma 3 case (4) for p = 11 forces Fix(ℤ₁₁) to be a pentagon (= Lemma 4 case 4 / Lemma 16 case 4). Lemma 19 case (3) further forces the 11-Sylow to be cyclic: X ≅ ℤ₁₁, no ℤ₁₁². No direct exclusion at order 11 — the single group ℤ₁₁ is paper-allowed.

Group classification

SmallGroupGroupDescriptionPaperLean
(11, 1) ℤ₁₁ Cyclic; Fix(ℤ₁₁) = pentagon (Lem 3(4)); 11-Sylow forced cyclic (Lem 19(3)). allowed open

Project status

open — no natural-language proof or Lean formalization yet. See Contribute for pointers if you want to attack this case.