double factorial (English, noun)
expansion: double factorial (plural double factorials)
Senses:
topics: combinatorics
mathematics
sciences
glosses: For an odd integer, the result of multiplying all the odd integers from 1 to the given number; or for an even integer, the result of multiplying all the even integers from 2 to the given number; symbolised by a double exclamation mark (!!). For example, 9!! = 1 × 3 × 5 × 7 × 9 = 945.
Forms:
form: double factorials
tags: plural