Question 849725
Sn = (A1 + An)/2 * n 

1390 = (3+136)/2 * n

2780 = 139n

n = 20

136 = 3 + (20-1)*d

136 = 3 + 19d

133 = 19d

d = 7

3, 3+7, 3+2*7

3,10,17