This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A068951 #5 Oct 17 2020 18:15:52
%S A068951 2,3,5,7,2,5,11,5,7,11,7,13,11,17,2,5,5,11,13,7,13,11,17,11,13,17,19,
%T A068951 7,11,13,7,11,17,11,13,5,7,11,7,13,11,17,13,19,19,5,13,7,11,17,11,13,
%U A068951 17,19,17,13,19,17,23,7,13,11,13,17,13,17,17,13,19,13,19,17,23,17,11,13
%N A068951 Scan the primes, record digit-sum if it is itself prime.
%e A068951 a(13)=5 since the 13th prime is 41 and 4+1=5, which is prime.
%p A068951 dig := X->convert((convert(X,base,10)),`+`); a := n->`if`(isprime(dig(ithprime(n)))=true,dig(ithprime(n)),printf(""));
%t A068951 Select[Total[IntegerDigits[#]]&/@Prime[Range[200]],PrimeQ] (* _Harvey P. Dale_, Oct 17 2020 *)
%Y A068951 Cf. A046704.
%K A068951 easy,nonn,base
%O A068951 1,1
%A A068951 Francois Jooste (phukraut(AT)hotmail.com), Mar 10 2002