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A261371 Prime numbers that sum to a prime when added to their digital root. 0

%I

%S 11,13,29,53,67,71,89,101,103,137,191,193,227,229,233,269,281,359,431,

%T 449,461,463,499,569,593,641,643,659,683,701,719,769,821,823,857,859,

%U 877,967,1019,1061,1091,1093,1223,1289,1439,1451,1487,1489,1579,1597,1601,1619

%N Prime numbers that sum to a prime when added to their digital root.

%F (a(n) mod 9) mod 2 = 0. - _Altug Alkan_, Sep 28 2015

%e 11 (prime) + 2 (its digital root) = 13 (prime);

%e 89 (prime) + 8 (its digital root) = 97 (prime).

%t Select[Prime[Range[300]], PrimeQ[# + Mod[#, 9]] &] (* _Vincenzo Librandi_, Sep 29 2015 *)

%o (PARI) lista(nn) = forprime(p=2, nn, if (isprime(p + p%9), print1(p, ", "))); \\ _Michel Marcus_, Sep 12 2015

%o (MAGMA) [p: p in PrimesUpTo(2000) | IsPrime(p+(p mod 9))]; // _Vincenzo Librandi_, Sep 29 2015

%Y Cf. A000040, A010888, A038194.

%K nonn,base

%O 1,1

%A _Gary Croft_, Sep 11 2015

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Last modified August 17 23:58 EDT 2017. Contains 290682 sequences.