The story
Named after Italian mathematician Enrico Ducci (1864–1940), who discovered in the 1930s that every such sequence eventually becomes periodic.
Etymology from Wiktionary, CC BY-SA 4.0.
Ducci sequence
Today it means: A sequence of n-tuples of integers (a_1,a_2,...,a_n), such that the next n-tuple in the sequence is formed by taking the absolute differences of neighbouring integers: (a_1,a_2,...,a_n)→(|a_1-a_2|,|a_2-a_3|,...,|a_n-a_1|),. Full definition →