def gen_circular_primes(primeList, bound):
"""Generate circular primes until the bound is reached.
"""
extend_primes(primeList, bound)
for p in primeList:
# test if circular
isCircular = True
for rot in gen_rotations(p):
if binary_search(rot, primeList) < 0:
isCircular = False
break
if isCircular:
yield p
def is_abundant_splittable(n, primes = None, abundants = [12]):
"""Given number n, return True if it can be witeen as a sum of two abundant numbers."""
if abundants[-1] < n - 12:
expand_abundants(n, primes, abundants)
halfIndex = len(abundants) // 2
for i in xrange(0, len(abundants)):
abundant = abundants[i]
if listutils.binary_search(n-abundant, abundants, i, len(abundants)-1) >= 0:
return True
if abundant > (abundants[-1] // 2 ):
break
return False
