(geology) A very large-scale lithostratigraphic sequence in the rock record that represents a complete cycle of marine transgression and regression on a craton over a geologic time scale.

(algebra) An exact sequence of precisely three nontrivial objects (e.g., modules).

The infinitely long binary sequence obtained by starting with 0 and successively appending the Boolean complement of the sequence obtained thus far.

The oldest surviving arrangement of the 64 hexagrams of the I Ching.

(mathematics) A cyclic sequence (of order n on a size-k alphabet A) in which every possible length-n string on A occurs exactly once as a substring (i.e. a contiguous subsequence). Such a sequence is denoted by B(k, n).

plural of de Bruijn sequence

An exact sequence with countably infinitely many terms.

plural of long exact sequence

(biochemistry) A ribosomal binding site in the mRNA of prokaryotes.

plural of short exact sequence