What is the rule for sequence 4 9 18 31 48 69?

Answer 1

72

Answer 2

There are many possible answers but a relatively straightforward one is

Un = 2n2 - n + 3 for n = 1, 2, 3, ...

Answer 3

The rule for the sequence 4, 9, 18, 31, 48, 69 is that each number is obtained by adding a consecutive odd number starting from 3.

Starting with 4, we add 3 to get 7, then add 5 to get 12, then add 7 to get 19, then add 9 to get 28, and finally add 11 to get 39.

Therefore, the next number in the sequence should be 39.