20
1.5
13 18 16 21 19 24 22 27 25 ... . This series consists of adding 5 to the first number and subtracting 2 from the next number, repeating the sequence in that order.
The pattern is +2 /2 +3 /3 +4 /4, and the next term would be +5, or 8.
The next number in the sequence is 48.
20
8 and then 1.6
If the last number is 1/3 (it should be), the next number is 5 and 1/3
21
The next is 3.
39. The rule here is starting with the number 9, add (-6 + sequence number * 6). 9 + (-6) = 3 3 + 0 = 3 3 + 6 = 9 9 + 12 = 21 21 + 18 = 39 39 + 24 = 63
1.5
13 18 16 21 19 24 22 27 25 ... . This series consists of adding 5 to the first number and subtracting 2 from the next number, repeating the sequence in that order.
The pattern is +2 /2 +3 /3 +4 /4, and the next term would be +5, or 8.
The next number in the sequence is 48.
612
81