 # R Program to print the Fibonacci Sequence

October 11, 2021, Learn eTutorial
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## What is Fibonacci Series

A Fibonacci series is a sequence or series of numbers that start from 0, 1, 1, 2, 3, and so on. In the Fibonacci sequence, we add the first two numbers manually as 0 and 1. All the rest of the Fibonacci sequence is obtained by calculating the sum of the previous two numbers for example the third number of the Fibonacci sequence will be 0+1=1 and so on.

So in general we can define the nth term of a Fibonacci sequence will be calculated using the formula of finding the sum of (n-1)th and (n-2)th number. ## How Fibonacci Sequence is implemented in R Program

We are using `readline()` function for taking the user's input. Given below are the steps which are used in the R program to print Fibonacci Sequence. In this R program, we accept the user's input into the variable terms by providing an appropriate message to the user using '`prompt`'. In while loop finds the n'th term by adding the last two numbers.

### ALGORITHM

STEP 1: prompting appropriate messages to the user

STEP 2: take user input using `readline()` into variable total_terms

STEP 3: first set num1=0 , num2=1

STEP 4:check the variable total_terms is valid or not, if not re-enter the value

STEP 5:  if(total_terms >2), we use a `while` loop to find the next term

STEP 6:  in the `while` loop, we first print the two terms num1 and num2

STEP 7: calculate the next term nxt by adding the last two terms and printing it

STEP 8:update the values of num1 and num2 to the last two terms

STEP 9:continue until the number of terms reaches the total_terms

## R Source Code

```                                          ```# Take input from user
total_terms   = as.integer(readline(prompt="How many terms? "))

num1 = 0 # first number
num2 = 1 # second number
count = 2
# check if the total_terms  is valid
if (total_terms  <= 0) {
} else {
if (total_terms == 1) {
print("Fibonacci sequence:")
print(num1)
} else {
print("Fibonacci sequence:")
print(num1)
print(num2)
while (count < total_terms  ) {
nxt = num1 + num2
print(nxt)
# update values
num1 = num2
num2 = nxt
count = count + 1
}
}
}```
```

## OUTPUT

```How many terms? 10
 "Fibonacci sequence:"
 0
 1
 1
 2
 3
 5
 8
 13
 21
 34```

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