(Membership)
178, 177, 175, 169, 145,....
and the difference between 177 and 175 is 2, but the difference between 175 and 169 is 6, and the difference between 169 and 145 is 24, so as we can realize, it is a sequence,
(1),
(1).(2)=2,
(1).(2).(3)=6,
(1).(2).(3).(4)=24.
From this, it is so easy to see that the next difference should be
(1).(2).(3).(4).(5)=120.
By subtracting 120 from 145, we get 25, which is the next number.