5,17,29,41,53,65,?
16
Arithmetic
They are: 17+12 = 29 and 17-12 = 5
The sequence interval is 2 4 6 8 ( this is the difference of number). so the missing number is -1 if I'm not mistaken.
-47, -41, -35, -29, -23, -17, -11, -5, 1, etc.
29
16
Arithmetic
They are: 17+12 = 29 and 17-12 = 5
The Least Common Multiple of 29 and 17 is 493.
The GCF of 17 and 29 is 1.1
21
The pattern of odd numbers
5, 11, 17, 23, 29
-29.
The GCF is 1.
t(n) = 12*n + 5