U(20)=(1,3,7,9,11,13,17,19).
ord(20)=8
ord(3)=ord(17)=ord(7)=ord(13)=4,ord(19)=ord(9)=ord(11)=2
So since no element has order 8, no element can generate U(20).\
--Johns121 22:17, 2 February 2009 (UTC)
U(20)=(1,3,7,9,11,13,17,19).
ord(20)=8
ord(3)=ord(17)=ord(7)=ord(13)=4,ord(19)=ord(9)=ord(11)=2
So since no element has order 8, no element can generate U(20).\
--Johns121 22:17, 2 February 2009 (UTC)
