3,18,60,147,( Such as the title

3,18,60,147,( Such as the title

3 18 60 147 297
The difference between the two numbers is 15 42 87 150
15=3*5 42=3*14 87=3*29 150=3*50
The difference between them is 3 * 9 and 3 * 15 3 * 21
Each number is 3 * 6 = 18

4, 13, 36, (), 268. What should be in brackets

97

(), 36,19,10,5,2. What's the attitude of this sequence? What's in the brackets?

Looking from the back to the front, the differences between the two numbers are 3, 5, 9, 17... Respectively. The latter number is equal to 2 times of the former number - 1, so the next difference is 33, so the value in brackets is 66