Observe the number arrangement in the table below. The second number in the nth row (n ≥ 2) is___ ．

The second number in the nth line (n ≥ 2) is 2, 4, 7, 11, 16 respectively Denote as sequence {an}, then a3-a2 = 2, a4-a3 = 3 So A3 = A2 + 2, A4 = A3 + 3 = A2 + 2 + 3 So an = A2 + 2 + 3 + 4 + +(n-1) = 2 + (n-2) (2 + n-1) 2 = n2-n + 22

RELATED INFORMATIONS

1. The following is a regular number table, please use the algebraic expression with n to represent the number of n-th row and n-th column in the number table First column second column third column fourth column First line 1 2 5 10 The second line 4 3 6 11 The third line 9 8 7 12 The fourth line 16 15 14 13 .....
2. Number reasoning: 2,3,13,45, (), the numbers in brackets are Please provide the calculation process, tks~
3. Number reasoning: - 3, - 2, - 1,6,25, (), the number in brackets should be? 58 、62、66、70
4. What number should brackets be
5. What are the numbers in brackets 1,2,2,4,8, ()?
6. May I ask the rule of 1.2.4.7.11. (). (). What number should be filled in brackets?
7. According to the number provided, infer what number should be filled in the brackets? 0.1.3.6.10.15.21
8. Numerical reasoning: 0.0.1.4. () what should be filled in brackets and why?
9. How many four digit numbers can be arranged by using the six numbers 1, 2, 3, 4, 5 and 6?
10. After 1,2,3,4,5,6 are written in a row in any order, the three adjacent numbers can form four 3-digit numbers according to their order in the arrangement The maximum value of the sum of these three digits is
11. Arrange some numbers in the following table: the first column, the second column, the third column, the fourth column, the first row 14510, the second row 481012, the third row 9121514? (2) What are the rows and columns of the number 81? (3) What are the rows and columns of the number 100?
12. Arrange the natural numbers from 1 to 100 as shown in the following table. In this table, the long side has three numbers and the wide side has two numbers Arrange the natural numbers from 1 to 100 as shown in the table. In this table, surround the three numbers on the long side and the two numbers on the wide side with a rectangular box. The sum of the six numbers is 87. In other parts of the table, the sum of the six numbers enclosed as mentioned above is 429? 1 2 3 4 5 6 7 8 9 （10 11 12 ） 13 14 15 16 （17 18 19 ） 20 21 ......................................... .................................. .............................................97 98 99 100
13. The following table is arranged according to a certain rule. The number 88 in the eighth row of the table is______ ．
14. A cube is a three-dimensional figure surrounded by six squares. Is it right or wrong? Notice I'm in grade five
15. Have you ever judged how many cubes there are according to the three views of the three-dimensional figure made of several cubes? The more the better!
16. A cube is made up of six identical elements______ A three-dimensional figure formed by a circle
17. A three-dimensional figure has six small cubes from the top, and six small cubes from the front and side. How many small cubes does this figure form consist of
18. The number of cubes in each layer is 1, 3, 6 How many cubes are there in layer N?
19. The positive odd numbers 1,3,5,7 Arrange in five columns according to the format shown in the figure. What is the row and column of 2005? The positive odd numbers 1,3,5,7 Arrange in five columns according to the format shown in the figure. What is the row and column of 2007? The positive odd numbers are arranged in 5 columns as follows: First column second column third column fourth column fifth column First line 1 3 5 7 The second line 15 13 11 9 The third line 17 19 21 23 The fourth line 31 29 27 25
20. The matrix of Figure 1 is composed of odd numbers Figure 1 1 3 5 7 9 11 13 15 17 19 ………………………… 91 93 95 97 99 5. 7, 13, 15 are framed together (1) Look at the relationship between the four numbers in the box in Figure 1. Please use letters to indicate the relationship between the four numbers in such a box (2) If the sum of the four numbers framed in this way is 200, calculate the four numbers (3) Is there such four numbers whose sum is 400? Why?