What is the next digit of the series 1, 2, 3, 5, 7 ..................?

A 9

B 14

C 11

D 16

Solution

Correct Answer: Option C

I would guess that the formula is meant to be:

a1 = 1 a2 = 2 a3 = 3 a4 = 5 a5 = 7 an = 6 + a(n–2)