1. Observe the following column number: - -. 2, 6, 12, 20. Please find out the rule of arrangement and fill in according to this rule 1 1 1 1 Look at the following number of columns: ---- 2 ， 6 ， 12 ， 20 Please find out the rule of arrangement and fill in the blanks according to the rule (1) The ninth number is___ The fourteenth number is. (2) If n is an integer greater than 1, write the nth number according to the above arrangement

1. Observe the following column number: - -. 2, 6, 12, 20. Please find out the rule of arrangement and fill in according to this rule 1 1 1 1 Look at the following number of columns: ---- 2 ， 6 ， 12 ， 20 Please find out the rule of arrangement and fill in the blanks according to the rule (1) The ninth number is___ The fourteenth number is. (2) If n is an integer greater than 1, write the nth number according to the above arrangement

Are your questions all fractions? The numerator is 1
The law of denominator is as follows
2=1*2
6=2*3
12=3*4
20=4*5
Rule: the denominator of the nth number is = n (n + 1)
The denominator of the ninth number is 90 (9 * 10), and the score is 1 / 90
The denominator of the 14th number is 210, and the fraction is 1 / 210
The nth number is 1 / N (n + 1)