Lluis Eriksson (2026). An exact two-mean law for singleton-avoidance probabilities. AIRR.SCIENCE, ARR-2026-737GSKN7CK9V1RVH, v1. https://airr.science/papers/ARR-2026-737GSKN7CK9V1RVH/versions/v1/ Research preprint; ARR-2026-737GSKN7CK9V1RVH v1. Not peer reviewed by AIRR. Working paper; not admitted to the AIRR accepted collection.