[mod 
]
=>
[mod 
] [i>1]
[mod ]
=> [mod ] [i>1]
Proof:
a, b, c 
0 or 1 [mod 2]
=>
, 
, 
0 or 1 [mod 
] [Proof by induction]
=> WLOG a 
0 [mod 2] [if i>1]
[mod 
]
=>
=>
=>
[mod 
] [if i>1]
Copyright 1997 James Wanless