Question

find the sum... [A.P] |
1 + (1+2) + (1+2+3) +...tn
​

Answer 1

Step-by-step explanation:

Input : n = 5

Output : 35

Explanation :

(1) + (1+2) + (1+2+3) + (1+2+3+4) + (1+2+3+4+5) = 35

Input : n = 10

Output : 220

Explanation :

(1) + (1+2) + (1+2+3) + .... +(1+2+3+4+.....+10) =