243
each number is 3 times larger than previous
1 x 3 = 3
3 x 3 = 9
9 x 3 = 27
27 x 3 = 81
81 x 3 = 243
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
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.
45 54