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 A261371 #41 Sep 08 2022 08:46:13 %S A261371 11,13,29,53,67,71,89,101,103,137,191,193,227,229,233,269,281,359,431, %T A261371 449,461,463,499,569,593,641,643,659,683,701,719,769,821,823,857,859, %U A261371 877,967,1019,1061,1091,1093,1223,1289,1439,1451,1487,1489,1579,1597,1601,1619 %N A261371 Prime numbers that sum to a prime when added to their digital root. %F A261371 (a(n) mod 9) mod 2 = 0. - _Altug Alkan_, Sep 28 2015 %e A261371 11 (prime) + 2 (its digital root) = 13 (prime); %e A261371 89 (prime) + 8 (its digital root) = 97 (prime). %t A261371 Select[Prime[Range[300]], PrimeQ[# + Mod[#, 9]] &] (* _Vincenzo Librandi_, Sep 29 2015 *) %o A261371 (PARI) lista(nn) = forprime(p=2, nn, if (isprime(p + p%9), print1(p, ", "))); \\ _Michel Marcus_, Sep 12 2015 %o A261371 (Magma) [p: p in PrimesUpTo(2000) | IsPrime(p+(p mod 9))]; // _Vincenzo Librandi_, Sep 29 2015 %Y A261371 Cf. A000040, A010888, A038194. %K A261371 nonn,base %O A261371 1,1 %A A261371 _Gary Croft_, Sep 11 2015