n1n2nr

n1n2nr is not a widely standardized term in mathematics or computer science. As a string of characters, it is sometimes used in academic writing as a label to denote a parameterized object indexed by two natural numbers n1 and n2, together with a further parameter nr.

Definition and interpretation: The notation serves as a compact label rather than an operator. In a given context, n1n2nr may stand for the index triple (n1, n2, nr) or for the corresponding object F(n1, n2, nr) in a family of objects {F(n1, n2, nr)}. The precise meaning is defined by the author and is not universal.

Example: If a researcher defines a family of sequences a_{n1,n2,r} and uses the tag n1n2nr to refer to a_{n1,n2,r}, then specifying n1=2, n2=3, nr=5 identifies the element a_{2,3,5}.

Context and usage: Such labels are common in tables, databases, or compact notation in proofs where repeating indices would be cumbersome. To prevent ambiguity, authors typically accompany the label with a formal definition at first use.

See also: index notation; triple indexing; concatenation (in naming); mathematical notation conventions.