seq

Seq is an abbreviation for sequence and is used in several fields of computing and mathematics to denote an ordered list of terms or a tool that generates such lists. In computing, seq can refer to both a command-line utility and a programming construct designed to produce or manipulate sequences.

The seq command is part of GNU coreutils and related Unix utilities. It prints a sequence of numbers from a starting value to an ending value, optionally with a specified step size and formatting. It is commonly used in shell scripting to generate numeric lists for iteration, data generation, or pagination. Typical usage includes producing a simple range such as a sequence from one to five, or more complex sequences with a defined increment and custom output formatting.

In functional programming, seq is a standard function in languages like Haskell. It forces its first argument to be evaluated to weak head normal form before returning the second argument, enabling explicit control over evaluation order and memory usage. Its type is seq :: a -> b -> b, and it is primarily used to avoid unintended laziness and related space leaks.

In R, seq() is a built-in function that creates regular sequences. It accepts arguments such as from, to, by, and length.out, returning a numeric vector. It is widely used for generating index sequences, setting plotting ranges, and simulating data. Across mathematics and computer science, seq likewise denotes a sequence—a list of elements indexed in order, central to ideas in series, convergence, and discrete structures.