108
108
81
60.75
Based on the sample you have provided, I see that 4 numbers, counting by 2 from 12 to 18, form a repeating sequence. I would expect that the next 4 numbers in this series would again be 12, 14 16, and 18.
The number 7 comes next.
18
26
11
45 54
54
The pattern is add three and then multiply by three. The next number is 174.
Each number in the series is being multiplied by (2 + (n-1)) where n = the term in the series 3 x 2 = 6 6 x 3 = 18 18 * 4 = 72 72 x 5 = 360
18
The next number is 0
21
The next number in the series 4, 12, 6, 12, 36, 18, 36