Question

1+(1+2)+(1+2+3)+(1+2+3+4)... find the sum of the series

Answer 1

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) = 220

Answer 2

$1 + 3 + 6 + 9 = 19$
Hope it helps!!