数字197可以被称为循环素数,因为197的三个数位循环移位后的数字:197,971,719均为素数。100以内这样的数字包括13个,2,3,5,7,11,13,17,31,37,71,73,79,97。要求任意正整数n以内一共有多少个这样的循环素数。
count = 0
n = int(raw_input('n='))
for i in range(2,n):
bit = 0
mc = i
while mc != 0:
mc/=10
bit+=1
for j in range(2,i):
if i%j == 0:
break
else:
temp = 0
init = i
while temp != init:
flag = 0
many=i/10
single=i%10
temp=single*(10**(bit-1))+many
for k in range(2,temp):
if temp%k == 0:
flag+=1
break
else:
i = temp
if flag ==1:
break
if flag == 0:
count+=1
print count