the odd natural numbers have been divided in group as; (1,3);(5,7,9,11);(13,15,17,19,21,23);………….. show that the sum of numbers in the nth group is 4ncube

the odd natural numbers have been divided in group as; (1,3);(5,7,9,11);(13,15,17,19,21,23);………….. show that the sum of numbers in the nth group is 4ncube