Fibonacci Sequence - Definition, List, Formulas and Examples (2024)

The Fibonacci sequence is a type series where each number is the sum of the two that precede it. It starts from 0 and 1 usually. The Fibonacci sequence is given by 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, and so on. The numbers in the Fibonacci sequence are also called Fibonacci numbers. In Maths, the sequence is defined as an ordered list of numbers that follow a specific pattern. The numbers present in the sequence are called the terms. The different types of sequences are arithmetic sequence, geometric sequence, harmonic sequence and Fibonacci sequence. In this article, we will discuss the Fibonacci sequence definition, formula, list and examples in detail.

Table of Contents:
  • Definition
  • Formula
  • Sequence List
  • Golden Ratio to Calculate Fibonacci Sequence
  • Solved Examples
  • Practice Problems
  • FAQs

What is Fibonacci Sequence?

The Fibonacci sequence, also known as Fibonacci numbers, is defined as the sequence of numbers in which each number in the sequence is equal to the sum of two numbers before it. The Fibonacci Sequence is given as:

Fibonacci Sequence = 0, 1, 1, 2, 3, 5, 8, 13, 21, ….

Here, the third term “1” is obtained by adding the first and second term. (i.e., 0+1 = 1)

Similarly,

“2” is obtained by adding the second and third term (1+1 = 2)

“3” is obtained by adding the third and fourth term (1+2) and so on.

For example, the next term after 21 can be found by adding 13 and 21. Therefore, the next term in the sequence is 34.

Fibonacci Sequence Formula

The Fibonacci sequence of numbers “Fn” is defined using the recursive relation with the seed values F0=0 and F1=1:

Fn = Fn-1+Fn-2

Here, the sequence is defined using two different parts, such as kick-off and recursive relation.

The kick-off part is F0=0 and F1=1.

The recursive relation part is Fn = Fn-1+Fn-2.

It is noted that the sequence starts with 0 rather than 1. So, F5 should be the 6th term of the sequence.

Fibonacci Sequence List

The list of first 20 terms in the Fibonacci Sequence is:

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181.

The list of Fibonacci numbers are calculated as follows:

FnFibonacci Number
00
11
21
32
43
55
68
713
821
934
… and so on.… and so on.

Golden Ratio to Calculate Fibonacci Numbers

The Fibonacci Sequence is closely related to the value of the Golden Ratio. We know that the Golden Ratio value is approximately equal to 1.618034. It is denoted by the symbol “φ”. If we take the ratio of two successive Fibonacci numbers, the ratio is close to the Golden ratio. For example, 3 and 5 are the two successive Fibonacci numbers. The ratio of 5 and 3 is:

5/3 = 1.6666

Take another pair of numbers, say 21 and 34, the ratio of 34 and 21 is:

34/21 = 1.619

It means that if the pair of Fibonacci numbers are of bigger value, then the ratio is very close to the Golden Ratio.

So, with the help of Golden Ratio, we can find the Fibonacci numbers in the sequence.

The formula to calculate the Fibonacci numbers using the Golden Ratio is:

Xn = [φn – (1-φ)n]/√5

Where,

φ is the Golden Ratio, which is approximately equal to the value of 1.618

n is the nth term of the Fibonacci sequence.

Related Articles

  • Sequence And Series
  • Arithmetic Progression
  • Geometric Progression
  • Harmonic Progression

Fibonacci Sequence Solved Examples

Example 1:

Find the Fibonacci number when n=5, using recursive relation.

Solution:

The formula to calculate the Fibonacci Sequence is: Fn = Fn-1+Fn-2

Take: F0=0 and F1=1

Using the formula, we get

F2 = F1+F0 = 1+0 = 1

F3 = F2+F1 = 1+1 = 2

F4 = F3+F2 = 2+1 = 3

F5 = F4+F3 = 3+2 = 5

Therefore, the fibonacci number is 5.

Example 2:

Find the Fibonacci number using the Golden ratio when n=6.

Solution:

The formula to calculate the Fibonacci number using the Golden ratio is Xn = [φn – (1-φ)n]/√5

We know that φ is approximately equal to 1.618.

n= 6

Now, substitute the values in the formula, we get

Xn = [φn – (1-φ)n]/√5

X6 = [1.6186 – (1-1.618)6]/√5

X6 = [17.942 – (0.618)6]/2.236

X6 = [17.942 – 0.056]/2.236

X6 = 17.886/2.236

X6 = 7.999

X6 = 8 (Rounded value)

The Fibonacci number in the sequence is 8 when n=6.

Practice Problems

  1. Find the Fibonacci number when n = 4, using the recursive formula.
  2. Find the next three terms of the sequence 15, 23, 38, 61, …
  3. Find the next three terms of the sequence 3x, 3x + y, 6x + y, 9x + 2y, …

Frequently Asked Questions on Fibonacci Sequence

Q1

What is Fibonacci Sequence?

The Fibonacci sequence is the sequence of numbers, in which every term in the sequence is the sum of terms before it.

Q2

Why is Fibonacci sequence significant?

The Fibonacci sequence is significant, because the ratio of two successive Fibonacci numbers is very close to the Golden ratio value.

Q3

What are two different ways to find the Fibonacci Sequence?

The two different ways to find the Fibonacci sequence are

  1. Recursive Relation Method
  2. Golden Ratio Method

Q4

Write down the list of the first 10 Fibonacci numbers.

The list of the first 10 Fibonacci numbers are 0, 1, 1, 2, 3, 5, 8, 13, 21, 34.

Q5

What is the value of the Golden ratio?

The value of golden ratio is approximately equal to 1.618034…

Fibonacci Sequence - Definition, List, Formulas and Examples (2024)

FAQs

Fibonacci Sequence - Definition, List, Formulas and Examples? ›

The Fibonacci sequence is a type series where each number is the sum of the two that precede it. It starts from 0 and 1 usually. The Fibonacci sequence is given by 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, and so on. The numbers in the Fibonacci sequence are also called Fibonacci numbers.

What is the formula and example of Fibonacci sequence? ›

Fibonacci sequence, the sequence of numbers 1, 1, 2, 3, 5, 8, 13, 21, …, each of which, after the second, is the sum of the two previous numbers; that is, the nth Fibonacci number Fn = Fn 1 + Fn 2.

What is the Fibonacci sequence with example? ›

The Fibonacci sequence is a set of steadily increasing numbers where each number is equal to the sum of the preceding two numbers. Many things in nature have dimensional properties that adhere to the golden ratio of 1.618, a quotient derived from the Fibonacci sequence.

What is the list of the Fibonacci sequence? ›

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, ... Try this Fibonacci Calculator, written in JavaScript.

What are the first 100 terms of the Fibonacci sequence? ›

First 100 terms of Fibonacci series are :- 0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765 10946 17711 28657 46368 75025 121393 196418 317811 514229 832040 1346269 2178309 3524578 5702887 9227465 14930352 24157817 39088169 63245986 102334155 165580141 267914296 433494437 701408733 1134903170 ...

Why is 1.618 so important? ›

The golden ratio, also known as the golden number, golden proportion, or the divine proportion, is a ratio between two numbers that equals approximately 1.618. Usually written as the Greek letter phi, it is strongly associated with the Fibonacci sequence, a series of numbers wherein each number is added to the last.

What is an example of a Fibonacci like sequence? ›

Many examples of events in the universe that follow the Fibonacci sequence and its golden ratio, such as biological arrangements such as branching on trees, phyllotaxis (arrangement of leaves on the stem), pineapple sprouts, flowering artichokes, ferns that are not rounded and bract arrangement of pine cones and others ...

How to calculate Fibonacci? ›

We can calculate any Fibonacci number using this Golden Ratio as per this formula: Fn = ((ɸ)n−(1−ɸ)n) ÷ √5. Here, ɸ = 1.618034.

How do you explain the Fibonacci sequence in nature? ›

In trees, the Fibonacci begins in the growth of the trunk and then spirals outward as the tree gets larger and taller. We also see the golden ratio in their branches as they start off with one trunk which splits into 2, then one of the new branches stems into 2, and this pattern continues.

What is the recursive formula for the Fibonacci sequence? ›

The Fibonacci Algorithm is a numerical series where each number is the sum of the two preceding ones, starting from 0 and 1. It's a simple and significant concept in computer science with base cases F(0) = 0, F(1) = 1, and recursive case F(n) = F(n-1) + F(n-2).

How is Fibonacci used in real life? ›

These numbers are used in various fields such as architecture, art, space exploration, engineering, technology, and computing. The Fibonacci sequence, also known as the golden ratio, is utilized in architectural designs, creating aesthetically pleasing structures 1.

What does Fibonacci mean in life? ›

The spiritual meaning of the Fibonacci spiral is often associated with balance, harmony, and perfection. Some believe that this pattern represents the infinite and interconnected nature of all things. It symbolizes the natural order and balance found in the universe and signifies the beauty and efficiency of creation.

Why is the Fibonacci sequence so important? ›

The Fibonacci sequence is important for many reasons. In nature, the numbers and ratios in the sequence can be found in the patterns of petals of flowers, the whorls of a pine cone, and the leaves on stems. As the sequence continues, the ratios of the terms approach a number known as the golden ratio.

What is the Fibonacci equation? ›

Using this numbering, the Fibonacci sequence can be defined by the following three equations: F0 = 0 (applies only to the first integer) F1 = 1 (applies only to the second integer) Fn = Fn-1 + Fn-2 (applies to all other integers)

What is the 1000th Fibonacci number? ›

If we are assuming that the first and second terms are both 1, then the 1000th term is 43466557686937456435688527675040625802564660517371780402481729089536555417949051890403879840079255169295922593080322634775209689623239873322471161642996440906533187938298969649928516003704476137795166849228875.

What is the formula for golden ratio and Fibonacci sequence? ›

The golden ratio is derived by dividing each number of the Fibonacci series by its immediate predecessor. In mathematical terms, if F(n) describes the nth Fibonacci number, the quotient F(n)/ F(n-1) will approach the limit 1.618... for increasingly high values of n. This limit is better known as the golden ratio.

What is the sequence formula? ›

The formula for the nth term in an arithmetic sequence is an=a1+(n−1)d. This formula can be used to determine the value of any term in an arithmetic sequence. An arithmetic sequence has a common difference between every term.

What is the formula for the nth Fibonacci numbers? ›

For example, lets set Fibonacci Sequence to f, and any place in the sequence is n, if we want to get f(nth place) we would add f(n-1) and f(n-2). Mathematically, it would look like f(n-2)+f(n-1)=f(n).

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