221

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The two cicada broods, 13-year cicada and the 17-year cicada (whose development times has curious connections to prime numbers), emerge together once in 221 years. It happened in 2024 and would next happen in 2245. [Gudipati]

Submitted: 2026-06-05 03:30:17; Last Modified: 2026-06-05 11:52:39.