double factorial

Noun

 * 1)  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.

Translations

 * Catalan: doble factorial
 * Dutch: dubbelfaculteit
 * Esperanto: duopa faktorialo
 * French: double factorielle
 * German: Doppelfakultät, doppelte Fakultät
 * Portuguese: duplo fatorial
 * Spanish: doble factorial
 * Thai: ดับเบิลแฟกทอเรียล