What is the next number in the following series - 9 , 19 , 39 , 79 , ??

Question

What is the next number in the sequence -
1, 7, 10, 13, 19, 23, 28, 31, 32, 44, 49, 68, 70, 79, 82, 86, 91, 94, 97, 100, 103, 109, 129, 130, ?

Answer 1

As per the given series ( 9, 19, 39, 79 .. ?)

next_number = (number + 10 * (1, 2, 4, 8, ..)), i.e

9  + (10 * 1) = 19
19 + (10 * 2) = 39
39 + (10 * 4) = 79
79 + (10 * 8) = 159

One more solution is:
next_number = (number * 2) + 1

9 * 2 + 1  = 18  + 1 ==> 19
19 * 2 + 1 = 38  + 1 ==> 39
39 * 2 + 1 = 78  + 1 ==> 79
79 * 2 + 1 = 158 + 1 ==> 159

Answer 2

answer is 159

Answer 3

159
9x2+1=19,19x2+1=39,39x2+1-79,79x2+1=159

Answer 4

(9*2) + 1 = 19
(19*2) + 1 = 39
(39*2) + 1 = 79
(79*2) + 1 = 159

So answer is 159

Answer 5

10 added to 9, to get 19.
Double of 10, 20 added to 19 to get 39.
Double of 20, 40 added to 39 to get 79.
Double of 40, 80 added to 79 to get 159.