Question

Write a recursive formula for the sequence 15, 26, 48, 92, 180.

Answer 1

We are given the sequence 15, 26, 48, 92, 180. if we try to get the difference of the numbers, the sequence of the differences is 11,22, 44, 88.. this means the first difference is 11 and the succeeding differences is multiplied by 2 and so on. 

Answer 2

15, 26, 48, 92, 180

  26 - 15 = 13
  48 - 26 = 22
  92 - 48 = 44
180 - 92 = 88

  26 ÷ 15 = 1.73
  48 ÷ 26 = 1.84
  92 ÷ 48 = 1.9167
180 ÷ 92 = 1.95

The recursive formula isn't arithmetic or geometric.