Find the term sequence step by step

Question

0,2,5,9,_?

Answer 1

-1, -1, 0,2,5,9, 14, 20, 27, 35, 44, 54, 65, 77, 90, 104, 119, 135, ...

answer = 14 for 5th term of the sequence, if you count 0 as the 1st term,

the sequence is neither arithmetic or geometric

a1 = 0

a2 = 2

a3 =5

a4 = 9

a5 = 14

an = an-1 + n

a6 = 14+6 = 20

a7 = 20+7 = 27

etc.

Answer 2

a₁ = 0

a_n = a_n-1 + n