12345 and 54321 are the same number series

Sequences are sequential, so 12345 and 54321 are not the same sequence.

Each number in the sequence is called an item in the sequence. The number in the first place is called the first term of the series, the number in the second place is called the second term of the series, and so on, the number in the nth position is called the nth term of the series, which is usually denoted by an.

Functional comprehension of sequences:

A sequence is a special kind of function. Its particularity is mainly manifested in its defined domain.

and on the range. A sequence of numbers can be thought of as a set of positive integers that define the domain.

n* or a finite subset of its functions, where none can be omitted.

It is an important way to understand the sequence of numbers from the point of view of functions, and in general, there are three ways to represent functions, and sequences are no exception, and there are usually three ways to represent them: alist method; b。

image method; c.Analytical. The analytic method includes giving a series of numbers with a general formula and a recursive formula.

Give the sequence. Functions don't necessarily have analytic formulas, and sequences don't all have universal formulas.

A sequence of number is a function of a set of positive integers (or a finite subset of it) as a domain defined by a sequence of ordered numbers.

In short, there is an order in the sequence.

The general formula for the first series is a(n)=n;

The general formula for the second sequence is a(n)=6-n.

So, it's two different sequences.

Solution: Let the first one be x. Then the second one is -5x, and the third one is 25xx+(-5x)+25x=2625

21x=2625x=125

These three numbers are 125, -625, 3125

This is a proportional series.

The common ratio is 5an=(-1) (n+1)*5 (n-1) so that the three numbers are: a, -5a, 25a then:

a-5a+25a=21a=-2625

a=-125

The three numbers are: 125, 625, 3125

Number series term = (-1) (n+1)*5 (n-1).

2625 (-1+5-25)=125, so the triple number is -125,625,-3125

The sequence 1 21 321 4321 54321n is characterized by the nth term an= i*10 (i-1)i=1, e.g. a5=5*10 4+4*10 3+3*10 2+2*10+1

1Soa2011= i*10 (i-1)i=2011

In the same way, the number series 1 12 123 1234 123451 so b2011= i*10 (2011-i)i=2011

It's 4, and I don't know if it's right (* hee-hee......