We show that if p ≠ 5 is a prime, then the numbers cover all the nonzero residue classes modulo p.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm96-2-4, author = {Florian Luca and Pantelimon St\u anic\u a}, title = {Products of factorials modulo p}, journal = {Colloquium Mathematicae}, volume = {96}, year = {2003}, pages = {191-205}, zbl = {1042.11002}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm96-2-4} }
Florian Luca; Pantelimon Stănică. Products of factorials modulo p. Colloquium Mathematicae, Tome 96 (2003) pp. 191-205. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm96-2-4/