# R Programming : Find the Fibonacci Sequence Using Recursive Function

Tutorial by:Maria Ghoste      Date: 2016-06-10 02:30:19

A Fibonacci sequence is the integer sequence of 0, 1, 1, 2, 3, 5, 8.... The first two terms are 0 and 1. All other terms are obtained by adding the preceding two terms. This means to say the nth term is the sum of (n-1)th and (n-2)th term.

## Source Code

``````# Program to diplay the Fibonacci
# sequence up to n-th term using
# recursive functions

recur_fibo <- function(n) {
if(n <= 1) {
return(n)
} else {
return(recur_fibo(n-1) + recur_fibo(n-2))
}
}

# take input from the user
nterms = as.integer(readline(prompt="How many terms? "))

# check if the number of terms is valid
if(nterms <= 0) {
print("Plese enter a positive integer")
} else {
print("Fibonacci sequence:")
for(i in 0:(nterms-1)) {
print(recur_fibo(i))
}
}``````

Output

```
How many terms? 9
[1] "Fibonacci sequence:"
[1] 0
[1] 1
[1] 1
[1] 2
[1] 3
[1] 5
[1] 8
[1] 13
[1] 21
```

Here, we ask the user for the number of terms in the sequence. A recursive function `recur_fibo()` is used to calculate the nth term of the sequence. We use a `for` loop to iterate and calculate each term recursively.

## R Programming

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