equation icon  [ ] [ ( ) 1 1 ] P0 = 1 + O(r2) P0 + r 1- ab_O_b aa + --r2aa + -r2Ra0b0_O_b + O(r3) Pa 2 2 1- a -1- tail = - 2qaa_O_ + 12(1 - 6q)qR + P0 + O(r)