20, 24, 28, 32, 36 ...
5, 13, 21, 29, 37 ...
8n - 3 = an
2n - 5 = an
-4, -2, 0, 2, 4 ...
2 (n - 3) = an
3, 5, 7, 9, 11 ...
4 ( n + 4) = an
-3, -1, 1, 3, 5 ...
(4n + 2) / 2 =
