243
25
-243
122
37
The next number is 49+8 = 57
The series is n3: 13, 23, 33 ...The next number is 216.
27
81
27
15
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.