( 1) 1、4、7、 10、( 13)、( 16)

(2)2、6、 18、54、 162、(486)、( 1458)、

(3) 1、3、7、 15、3 1、63、( 127)、(255)

(4)5、8、 12、 17、23、(30)、(38)

2. Divide the natural number 1~200 into ABC three groups according to the following methods.

Group A: 1, 6, 7, 12, 13, 18, ... Group B: 2, 5, 8,1,1. .....

(1) How many numbers are there in each group? What is the last one in each group?

There are 67 people in group A, 67 people in group B and 66 people in group C.

Group a 199 B/200 C 196.

(2) In which group is173?

In group b, number 58

Three.

(1) Write the number of each bracket on the fifth floor.

( 1 1)( 12)( 13)( 14)( 15)

(2) How many brackets are there from layer 1 to layer 7 * * *?

28

(3) What floor is the support numbered 100 on?

14th floor

4.( 1) What is the relationship between the sum of five in brackets and the middle number?

Five times the median.

(2) When the sum of five numbers is 1 15, can these five numbers be put in brackets?

(2 1)(22)(23)(24)(25)

I hope I can adopt and do it myself!