A=1/3 + 1/9 + 1/18 + 1/30 + 1/45 + ... + 1/570
= 1/3(1 + 1/3 + 1/6 + 1/10 + 1/15 + ... + 1/190)
=2/3(3/2 + 1/6 + 1/12 + 1/20 + 1/30 + .... + 1/380)
=2/3(3/2 + 1/2 - 1/3 + 1/3 - 1/4 + 1/4 - 1/5 + 1/5 - 1/6 + ... + 1/19 + 1/20)
=2/3(3/2+1/2-1/20)
=2/3.39/20
=13/10