Answer: B. n(n+1)/2
Explanation:
The numbers in this sequence can be acquired by using the formula;
= n(n+1)/2
For instance, if one wishes to find the 2nd term of the sequence which is 3;
= 2(2 + 1)/2
= 3
Or the 5th term which is 15;
= 5 ( 5 + 1)/2
= 15
The nth term is therefore = n(n+1)/2
