R Program to Print the Fibonacci Sequence

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.

You can also print the Fibonacci sequence using a recursive function. Learn more about how to print the Fibonacci sequence using recursion.

Example: Print Fibonacci Sequence

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

# first two terms
n1 = 0
n2 = 1
count = 2

# check if the number of terms is valid
if(nterms <= 0) {
    print("Plese enter a positive integer")
} else {
    if(nterms == 1) {
        print("Fibonacci sequence:")
        print(n1)
    } else {
        print("Fibonacci sequence:")
        print(n1)
        print(n2)
        while(count < nterms) {
            nth = n1 + n2
            print(nth)
            # update values
            n1 = n2
            n2 = nth
            count = count + 1
        }
    }
}

Output

How many terms? 7
[1] "Fibonacci sequence:"
[1] 0
[1] 1
[1] 1
[1] 2
[1] 3
[1] 5
[1] 8 

Here, we ask the user for the number of terms in the sequence. We initialize the first term to 0 and the seconde term to 1.

If the number of terms is more than 2, we use a while loop to find the next term in the sequence.

Inside the while loop, we first print the first two terms n1 and n2 respectively. Then, we calculate the next term nth by adding the last two terms and print it.

Now, we update the values of n1 and n2 to the last two terms, i.e. the term in n2 to n1 and the term we just calculated nth to n2.

This goes on until the number of terms reaches the nterms entered by the user.