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 A158217 #10 Apr 03 2023 10:36:11
%S A158217 2,3,5,7,11,23,41,43,61,101,113,131,151,223,241,311,313,331,401,421,
%T A158217 601,1013,1031,1033,1051,1103,1123,1213,1231,1301,1303,1321,2003,2111,
%U A158217 2113,2131,2203,2221,2311,3011,3121,3301,4001,4003,4021,4111,4201,5011,5101
%N A158217 Primes whose digit sum is a single-digit prime.
%H A158217 Chris Caldwell, <a href="https://t5k.org/lists/small/1000.txt">The First 1,000 Primes</a>
%e A158217 The digit sum of the prime 421 is 7, which is a single-digit prime.
%t A158217 okQ[n_]:=Module[{ans=Plus@@IntegerDigits[n]},ans<10&&PrimeQ[ans]]; Select[Prime[Range[1000]], okQ] (* _Harvey P. Dale_, May 27 2009 *)
%Y A158217 Cf. A159251.
%K A158217 base,nonn
%O A158217 1,1
%A A158217 _Parthasarathy Nambi_, Mar 14 2009
%E A158217 More terms from _Harvey P. Dale_, May 27 2009