challenge - prime numbers where sum of squared digits of prime number is also prime

[Didier Lachieze]

A quick HP Prime program providing the prime numbers between N & M fitting the requirement:

Code:

EXPORT PrCh(N,M)
BEGIN
  LOCAL n:=N-1,res:={};
  WHILE n<M DO
    n:=nextprime(n);
    IF isprime(ΣLIST((ASC(STRING(n))-48)^2)) THEN PRINT(n); res(0):=n; END;
  END;
  RETURN res;
END;

Call it with e.g. SIZE(PrCh(1,1000)) to know for how many primes less than 1000 the sum of squared digits of the number is prime.