1 1 1 1 1 1 ____ + _____ + -------- + -------- + --------- + ----------- 1乘3乘5 3乘5乘7 5乘7乘9 7
1111 1 1
____+ _____ + --------+ --------+ --------- +-----------
1乘3乘5 3乘5乘75乘7乘97乘9乘119乘11乘13 11乘13乘15