Consider a two-letter word AB, where A = APPLE, and B =BOY,Every time you see A replace it by APPLE and B by BOY, One obtains the following chain:AB -->APPLEBOY --> APPLEPPLEBOYOY --> APPLEPPLEPPLEBOYOYOY --> ...The length of each string goes like this2 --> 8 --> 14 --> 20 -->...It is not difficult toa_n =... Continue Reading →