node-multifactorial

The factorial of a number, written as n!, is defined as n! = n(n − 1)(n − 2)...(2)(1). Multifactorials generalize factorials as follows:

	n! = n(n − 1)(n − 2)...(2)(1)
	n!! = n(n − 2)(n − 4)...
	n!!! = n(n − 3)(n − 6)...
	n!!!! = n(n − 4)(n − 8)...
	n!!!!! = n(n − 5)(n − 10)...

In all cases, the terms in the products are positive integers.

If we define the degree of the multifactorial as the difference in successive terms that are multiplied together for a multifactorial (the number of exclamation marks), then the task is twofold: Write a function that given n and the degree, calculates the multifactorial. Use the function to generate and display here a table of the first ten members (1 to 10) of the first five degrees of multifactorial.

For more information, see: https://en.wikipedia.org/wiki/Factorial#Multifactorials

Install

$ npm install --save multifactorial

Usage

var multifactorial = require('multifactorial');

multifactorial(10, 1);
//=> 3628800

multifactorial(10, 4);
//=> 120

API

multifactorial(number, degree)

number

Required Type: Number

degree

Optional Type: Number Default: 1

License

MIT © Vinícius do Carmo