18
3 + 1 = 4
4 + 2 = 6
6 + 3 = 9
9 + 4 = 13
Etc. The next number in the sequence would be 18, then 25, and so on.
Ans 2.
The previous answer contains an error.
The next number in the sequence would be 18 (13 + 5),
after which comes 24 (18 + 6 ) not 25.
18
18
18
The next number would be 18. The sequence increases with +1, +2, +3... +5 etc. 13 + 5 = 18
13 20 12
It is 24+7 = 31
Continuing the sequence would be the the numbers 24, 31, 39.
18 (3+1 4+2 6+3 9+4 13+5)
Unless you specify the length of the sequence, it is infinite, and so no number completes it. Given no further information, I would say the next number is 18. However, check out the link to the OEIS which gives a number of alternatives.
18(3+1=4 // 4+2=6 // 6+3=9 // 9+4=13 // 13+5=18)
4
18 because 3 - 4 - 6 - 9 - 13 - x+1 +2 +3 +4 +513+5= 18 is the answer