Question

Which is the next number in the following series of numbers 3, six, nine, 15, 24, 39

Answer 1

a(1) = 3, a(2) = 6

For n = 1, 2, 3, .....,

a(n + 2) = a(n) + a(n + 1)

The next number is 24 + 39 = 63.