def problem130(): count = 0 n = 1 total = 0 while count < 25: if gcd(n,10) == 1 and not isPrime(n) and (n-1)%A(n) == 0: count += 1 total += n n+=1 return total
def problem179a(): GOAL = 10**5 #checker = primes(save=True,initial=False) primes = rwh_primes2(GOAL//2) previous = 0 # counting 2 count = 1 for n in range(3,GOAL): # If it n+1 is prime, we can skip this number if isPrime(n): sig = 2 else: sig = sigma(n,primes) if sig == previous: count += 1 previous = sig return count