Answer

问题及解答

列出这样一些特殊的素数, $p=d_1d_2\ldots d_n$ 是素数, 它的反转(reverse) $q=\mathrm{reverse}(p)=d_n d_{n-1}\ldots d_2 d_1$ 也是素数.

Posted by haifeng on 2020-09-01 20:57:30 last update 2020-09-01 21:52:10 | Edit | Answers (0)

列出这样一些特殊的素数, $p=d_1d_2\ldots d_n$ 是素数, 它的反转(reverse) $q=\mathrm{reverse}(p)=d_n d_{n-1}\ldots d_2 d_1$ 也是素数.

比如 91121 和 12119

 


使用 Calculator 进行验证.

>> isprime(91121)
in> isprime(91121)
This is function isprime
sqrtnum=301.862552
--------------------
we choose sqrtnum : 303
 ... since we use the traditional algorithm, ...
 ... please wait a minute ...
 ... ::: ... ::: ...
out> 91121 is a prime

------------------------

>> reverse(91121)
in> reverse(91121)
out> 12119

 

>> isprime(12119)
in> isprime(12119)
This is function isprime
sqrtnum=110.086330
--------------------
we choose sqrtnum : 111
 ... since we use the traditional algorithm, ...
 ... please wait a minute ...
 ... ::: ... ::: ...
out> 12119 is a prime