The difference between two successive numbers starts with 11 and and then reduces by 3 but the sign alternates at each step
4 + 11 = 15 . . . (11 - 3) = 8 but the sign changes so it becomes -8
15 - 8 = 7 . . . (8 - 3) = 5
7 + 5 = 12 . . .(5 - 3) = 2 but the sign changes so it becomes -2
12 - 2 = 10 . . .(2 - 3) = -1
10 - 1 = 9 . . .(-1 - 3) = -4 but the sign changes so it becomes 4
9 + 4 = 13 . . . and so on
12, 10 and 15 the are alternatively increased by 2 and 3
The difference between the successive numbers is 4. so the next three numbers could be 4, 0 and -4.
12
11, -10, 9
18 plus 4, minus 2
-12, 14, -16
-17, -22
12, 10 and 15 the are alternatively increased by 2 and 3
The next two numbers are 26 & 78.
The difference between the successive numbers is 4. so the next three numbers could be 4, 0 and -4.
10-12-20-23-29-43
12
12
21 and 13. The pattern is t(n) = (-n4 + 10n3 - 23n2 + 38n - 12)/12
11, -10, 9
18 plus 4, minus 2
eight