The next number in this sequence is 18. You're adding 1 to the difference of the previous two numbers. 4-3=1, 6-4=2 etc... so 18-13=5.
The sequence is t(n) = 0.5*(n2 - n + 6) where n = 1, 2, 3, ...
It is, of course, easy to find polynomials of order 3 or higher that would fit the sequence.
The next number in the sequence is 18. It's +1, +2, +3, +4, ....
18 3 +1 4 +2 6 +3 9 +4 13 +5 18 +6 24 +7 31 +8 39 +9 48 +10 58...
After 13, it's 18.
3, -6, 12, 4, 20, 13, 27, 21, 33 -9, +18, -8, +16, -7, +14, -6, +12
The next number would be 18.3, 4, 6, 9, 13To get from 3 to 4, you need to add one. To get from 4 to 6, you need to add two. To get from 6 to 9, you need to add three. And so on and so on.
18 is the answer and here is why:- 3+1=4 4+2=6 6+3=9 9+4=13 13+5=18
18. The pattern is 3+1=4, 4+2=6, 6+3=9, 9+4=13, so 13+5=18
18
18 (3+1 4+2 6+3 9+4 13+5)
18. 3+1=4, 4+2=6, 6+3=9, 9+4=13, 13+5=18.
The next number in the sequence is 18. It's +1, +2, +3, +4, ....
18
18
18
18
18
18 Add to previous number by 1 then 2 then 3 then 4 and 5 3+1=4 4+2=6 6+3=9 9+4=13 so then 13+5=18