15.
You need to first find both patterns.
from 3 to 2 to 6 is: -1, +4
from 6 to 4 to 9 is: -2, +5
from 9 to 6 to 12 is: -3, +6
from 12 to 8 to .... is: -4, ....
Now that you can see the pattern (-1, -2, -3 and +4, +5, +6) you can
apply it to the next number
The next number is the sequence 236175969, 48, 12 is 236175861.
The number 7 comes next.
26
11
The next number in the series 4, 12, 6, 12, 36, 18, 36
The next number is the sequence 236175969, 48, 12 is 236175861.
The number 7 comes next.
26
9
132
The series seems to be "add 3," so the next number in the series would be 12 followed by 15.
11
11
The number that comes next in the series 1 2 2 5 3 10 is 7. You get this number by subtracting the number 3 from the number 10.
24
12
The next number in the series 4, 12, 6, 12, 36, 18, 36