13, 8, 3, –2, –7, –12, –17, …
6,2,-2,-6-10,-14-18…
-11,-7,-3,1,5,9,13…
-7,-3,1,5,9,13,17,21…
3, 6, 9, 12, 15, 18, …
-13,-8,-3,2,7,12,17…
-11,-6,-1,4,14,19,24,…
4,2,0…
5n-18
4n-15
-4n+10
4n-11
n+3
–5n + 18
5n-16
6 – 2n