Find the rule 0, 3, 8 (), 24 () (the last bracket indicates the nth number)
0、3、8(15)、24、… (square of n-1)
0, 3, 8, 15, 24, what is the nth number?
N^2-1
This is a sequence. The difference between two adjacent numbers is 3, 5, 7, 9 (2n-1) is regular, so we can calculate the general term formula of this sequence
0, 3, 8, 15, 24. The twentieth number is the nth number
The 20th number: 399 the nth number: the square of n-1