S there many ways but the best way is just add the given two no.s and divide them by 2.then u will get a num then to get the next num u need to add the new num and any one of the iven nums.u will get a new num.

-75/15-15/75 whole divided by 2 
for the next
39/15-75/15 whole divided by 2
for the next
6/5-75/15whole divided by 2
for the next
31/15-75/15 whole divided by 2
44/30-75/15whole divided by 2