def problem21(n): result = 0 for a in xrange(2, n + 1): b = PrimeMethods.sopdf(a, 1) - a a_prime = PrimeMethods.sopdf(b, 1) - b if a == a_prime and a != b: #print((a, b)) result += a return result
def is_abundant(n): if n < 12: return False spd = PrimeMethods.sopdf(n, 1) - n return spd > n