? = 1/2- 1/3+ 1/4- 1/5+……+ 1/2n- 1/(2n+ 1)

1-Sn = 1- 1/2+ 1/3- 1/4+ 1/5+……- 1/2n+ 1/(2n+ 1)

= 1+ 1/2+ 1/3+……+ 1/(2n+ 1)-2( 1/2+ 1/4+……+ 1/2n)

= 1/(n+ 1)+ 1/(n+2)+……+ 1/(2n+ 1)

Then neither will i.

Then Sn= 1-ln2.