User blog comment:LittlePeng9/ITTM galore/@comment-65.26.80.144-20140319173225/@comment-1605058-20140320143100

1+1+2+1+3+1+4+1+5+...=(1+1+1+1+...)+(1+2+3+4+5+...)=ζ(0)+ζ(-1)=(-1/2)+(-1/12)=-7/12