this is a time complexity analysis equation associated with heap sort and building heap ,where n is the total number of nodes and k is the height of the tree.please give detail process of the derivation thank you!

2. Please give the detailed process" of the following equation derivation (note that answer without any process will be not accepted) Eisisk 21-1(k i)=21sisk-1 2k-i-1 * i s n * Eisisk-1