Display Fibonacci Series in Python

What You’ll Learn

Fibonacci starts with 0 and 1; each next term is the sum of the previous two. This tutorial covers n-term printing, a value-ceiling variant, memoized recursion, a live preview, worked Python examples, edge cases, and complexity.

📝 Problem & Approach

Print the first n Fibonacci terms, or all terms up to a maximum value.

# seeds: 0, 1
# first 10: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34
# <= 100:   ... ends at 89 (next is 144)

Inputs & Outputs

Minimal workflow

function print_first_n_fibonacci_terms(n):
    a = 0
    b = 1
    repeat n times:
        output a
        next = a + b
        a = b
        b = next

Method comparison

🔮 Live Preview

Print the first n terms using exact BigInt arithmetic.

Press “Print series”.

Examples Gallery

Three complete Python programs — first n terms, until a max value, and memoized recursive nth term. Click View Output to reveal sample console results.

def display_fibonacci_terms(n: int) -> None:
    if n <= 0:
        print("Need a positive term count.")
        return

    first, second = 0, 1
    parts = []
    for _ in range(n):
        parts.append(str(first))
        first, second = second, first + second

    print(f"Fibonacci series up to {n} terms: " + ", ".join(parts))


terms = 10
display_fibonacci_terms(terms)

Fibonacci series up to 10 terms: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34

def display_fibonacci_until(max_val: int) -> None:
    if max_val < 0:
        print("max_val must be nonnegative.")
        return

    a, b = 0, 1
    parts = []
    while a <= max_val:
        parts.append(str(a))
        a, b = b, a + b

    print(f"Fibonacci numbers <= {max_val}: " + " ".join(parts))


display_fibonacci_until(100)

Fibonacci numbers <= 100: 0 1 1 2 3 5 8 13 21 34 55 89

from functools import lru_cache


@lru_cache(maxsize=None)
def fib(k: int) -> int:
    if k < 0:
        raise ValueError("k must be nonnegative.")
    if k <= 1:
        return k
    return fib(k - 1) + fib(k - 2)


# 0-based: fib(0)=0, fib(1)=1, ..., fib(9)=34
for k in range(10):
    print(f"F({k}) = {fib(k)}")

F(0) = 0
F(1) = 1
F(2) = 1
F(3) = 2
F(4) = 3
F(5) = 5
F(6) = 8
F(7) = 13
F(8) = 21
F(9) = 34

🔎 Worked Walkthrough — First 6 Terms

Trace the two-variable update starting from (0, 1).

Printed so far: 0, 1, 1, 2, 3, 5.

⚖️ Facts Worth Knowing

Handy follow-ups interviewers sometimes ask.

🎯 Practice Problems

Try these variations to lock in the pattern.

Notes

⏱️ Time and Space Complexity

For interview printing tasks, the iterative approach is the right default. Extra space above ignores the output string/list size.

💡 Best Practices