1 1 1 1
- + - + - + + -
3*7 7*11 11*15 23*27

1/3*7 + 1/3*11 + 1/11*15 + 1/23*27 = = 11/3*7*11 + 7/3*7*11 + 1/11*3*5 + 1/23*9*3 = = 17/3*7*11 + 23*9/11*3*5*9*23 + 11*5/11*3*5*9*23 == 17/3*7*11 + 207/11*3*5*9*23 + 55/11*3*5*9*23 == 17/3*7*11 + 263/11*3*5*9*23 == 17*5*9*23/11*3*5*9*23*7 + 263*7/11*3*5*9*23*7 == 177797/11*3*5*9*23*7 == 177797/239085