$A= \lbrace 5n \mid -5 \leq n \leq 21 ,n \ ∈ Z ,(n,2)=1\rbrace $
$B= \lbrace n^3-1 \mid n \ ∈ \ W\rbrace $
$C= \lbrace n \mid n \ ∈ Z ,n \mid 9\rbrace $ یا $C= \lbrace n \mid n \ ∈ \ Z , \frac{9}{n} \ ∈ Z\rbrace$
$D= \lbrace \frac{2n-1}{2^n} \mid n \ ∈ W\rbrace $
$ E= \lbrace n!-2 \mid n∈ N\rbrace $
