If `S_1 = {2}, S_2 = {3,6}, S_3 = {4,8,16},S_4 = {5,10,20,40} .......` then the sum of numbers in the set `S_15` is

If N, the set of natural numbers is partitionaed into groups S_(1)={1},S_(2)={2,3},S_(3)={4,5,6,7},S_(4)={8,9,10,11,12,13,14,15},"....", find the sum of the numbers n C_(50).