my opinion, the answer is 220. how? the sequence are 4,5,5,7,14,17,51,55,... 5-4 = 1; 5(no in odd position)*1 = 5 (the number next to it) 7-5= 2; 7(no in odd position)*2 =14 (the number next to it) 17-14= 3; 17(no in odd position)*3 = 51 (the number next to it) 55-51=4;55(no in odd position)*4 = 220 (the answer