1 -3= -2 -2+6= 4 4 - 10= -6 -6 + 13 = 7 7 - 17 = -10 -10 + 20 = 10 10 - 24 = -14 Now if we look at the sequence 3 6 10 13 17 20 24 , the next is 27 Therefore -14 + 27 = 13 The answer is 13

13 is the answer.

The sequence below contains terms that doesn't have any perfect square factors (except 1). 2, 3, 5, 6, 7, 10, 11, 13, 14, 15...

What is the sum of the square-roots of the terms starting from 2 to the largest two-digit term?