lychrel.py

# prints lychrel candidate numbers up to 10000

lychrels = set()
not_lychrels = set()
seeds = set()

def is_palindrome(n):
	n_str = str(n)
	if n_str[::-1] == n_str:
		return True
	else:
		return False

def test_lychrel(n, rem_generations, first):
	if rem_generations == 0:
		return True
	if n in lychrels:
		return True
	if n in not_lychrels:
		return False

	if is_palindrome(n) and first == False:
		not_lychrels.add(n)
		return False

	rev = int(str(n)[::-1])
	next = n + rev
	is_lychrel = test_lychrel(next, rem_generations - 1, False)

	if is_lychrel == False:
		not_lychrels.add(n)
		return False
	if is_lychrel == True:
		if n < 10000:
			lychrels.add(n)
		return True

for i in range(10000):
	test_lychrel(i, 40, True)

lychrel_list = list(lychrels)
lychrel_list.sort()

print "Lychrels: ", lychrel_list