http://benji3up2kxewkqfcq7buxk2xd6zwy3zggnurkrm3l4cvwy2iipvyyad.onion/mirrors/gmpdoc/Factorial-Algorithm.html
,
where [x] is the integer part of x , and so on
recursively. The procedure can be best illustrated with an example, 23! = (23.21.19.17.15.13.11.9.7.5.3)(11.9.7.5.3)(5.3)2^{19} Current code collects all the factors in a single list, with a loop and no
recursion, and computes the product, with no special care for repeated chunks.