==See also==* Weird number== References ==* Richard K. Guy, "Unsolved Problems in Number Theory" (3rd ed), Springer Verlag, 2004 ISBN 0-387-20860-7; section B10.
* Richard K. Guy, "Unsolved Problems in Number Theory" (3rd ed), Springer Verlag, 2004 ISBN 0-387-20860-7; section B10.