OFFSET
1,1
EXAMPLE
a(13)=5 since the 13th prime is 41 and 4+1=5, which is prime.
MAPLE
dig := X->convert((convert(X, base, 10)), `+`); a := n->`if`(isprime(dig(ithprime(n)))=true, dig(ithprime(n)), printf(""));
MATHEMATICA
Select[Total[IntegerDigits[#]]&/@Prime[Range[200]], PrimeQ] (* Harvey P. Dale, Oct 17 2020 *)
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
Francois Jooste (phukraut(AT)hotmail.com), Mar 10 2002
STATUS
approved