n 75 --------------- 2*n - 1 n - 2 5 *3
2 - n 1 - 2*n n 3 *5 *75
3.0^(2.0 - n)*5.0^(1.0 - 2.0*n)*75.0^n
45
-n -2*n n 45*3 *5 *75