equation icon  1-_O_a = 1-wa + -1-aa- 3-abwbwa - 3abwbaa + 15(abwb)2 wa + 3-a0wa - 1-aa r2 s2 2s 2s 4 8 8 3 b 1- b 1- b c 1- b c + abw wa + 6Ra0b0w - 2 Rb0c0w w wa - 3 Rab0cw w + O(s)