4+4=128
the pattern is something like this that the we are adding the numbers that are serially being multiplied by the multiples of 4 :-
1(4) + 1(4) = 8 <1is being multiplied by 4 than is added with another 1 that is multiplied by 4>
2(8) + 2(8) = 32
3(12) + 3(12) = 72
4(16) + 4(16) = 128 <similarly as in the case of 1+1, here, 4 is first multiplied by 16 and then in added with 4 that is also multiplied by 16>
