79
note the differences in the terms are
5, 8, 11, 17 are not constant, check the second differences, that is the difference between each term in the first differences.
the second differences are 3, 3, 3 are constant
each first difference increases by + 3
Thus each first difference will be 5, 8, 11, 17, (20), (23), ....
Hence the term after 59 is 59 + 20 = 79 then 79 + 23 = 102
