fibonacci sequence formula code example

Example 1: fibonacci sequence python

# WARNING: this program assumes the
# fibonacci sequence starts at 1
def fib(num):
	"""return the number at index `num` in the fibonacci sequence"""
    if num <= 2:
        return 1
    return fib(num - 1) + fib(num - 2)

# method 2: use `for` loop
def fib2(num):
	a, b = 1, 1
	for _ in range(num - 1):
		a, b = b, a + b
	return a


print(fib(6))  # 8
print(fib2(6))  # same result, but much faster

Example 2: fibonacci sequence

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ...

Example 3: fibonacci sequence

def fibonacci(n):
    if n <= 0:
        return 0
    elif n == 1:
        return 1
    else:
        return fibonacci(n-1) + fibonacci(n-2)

Example 4: fibinachi

def fib(n):
  lisp = []
  
  for i in range(n):
    if len(lisp) < 3:
      if len(lisp) == 0:
        lisp.append(0)
      else:
        lisp.append(1)
    
    else:
      lisp.append(lisp[len(lisp)-1]+lisp[len(lisp)-2])
  
  return lisp