java please

Write a method called method3 that accepts an integer parameter n and returns a sum of the first n-1 terms of the sequence. In other words, the method should generate the following sequence to calculate sum: 1 1 1 1 + 3 n-1 + } + { ++ ... + For example, method4 (2) will return 1.0 since 1 = 1.0 1+ 3+ 4+...+1+1 method4 (15) will return 3.251562326562327, the result from 1 1 13 14 /* You may assume that the parameter n is nonnegative. */