n(n+1)/2 + 3
Note that the difference between two consecutive numbers increases by one each time.
25
add 5 each timer
After 13, it's 18.
The next number in the sequence is 18. It's +1, +2, +3, +4, ....
18
Tn = 1 + 3n
Dart Board
After 13, it's 18.
18
18
18
18
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
The next number in the sequence is 18. It's +1, +2, +3, +4, ....
18
18
12
18