The arrows in diagram are pointing to 30, 36, 42, 48 and so on
If we observe closely, these are all multiples of 6, and the jump is also of that of 6, i.e. the difference between two neighboring numbers is 6.
60 is the last number, which is the tenth multiple of 6., i.e. 6 x 10 = 60
Thus, the next numbers after 60 will be:
6 x 11 = 66