Definitions
In mathematics, additive primes are prime numbers for which the sum of their decimal digits are also primes.



Task
Write a program to determine (and show here) all additive primes less than 500.

Optionally, show the number of additive primes.



Also see

   the OEIS entry:   A046704 additive primes.
   the prime-numbers entry:   additive primes.
   the geeks for geeks entry: additive prime number.
   the prime-numbers fandom: additive primes.


Function Digsum(n) =
    digsum := 0;
    while n>0 do
        digsum := digsum + n|10;
        n:=n\10;
    od;
    digsum.;
 
nadd := 0;
!!'Additive primes below 500 are';
 
for p=1 to 500 do
    if Isprime(p) and Isprime(Digsum(p)) then
       !!(p,' -> ',Digsum(p));
       nadd := nadd+1;
    fi od;
 
!!('There were ',nadd);