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

11, 13, 29, 53, 67, 71, 89, 101, 103, 137, 191, 193, 227, 229, 233, 269, 281, 359, 431, 449, 461, 463, 499, 569, 593, 641, 643, 659, 683, 701, 719, 769, 821, 823, 857, 859, 877, 967, 1019, 1061, 1091, 1093, 1223, 1289, 1439, 1451, 1487, 1489, 1579, 1597, 1601, 1619

Offset

1,1

Links

Table of n, a(n) for n=1..52.

Formula

(a(n) mod 9) mod 2 = 0. - Altug Alkan, Sep 28 2015

Example

11 (prime) + 2 (its digital root) = 13 (prime);
89 (prime) + 8 (its digital root) = 97 (prime).

Mathematica

Select[Prime[Range[300]], PrimeQ[# + Mod[#, 9]] &] (* Vincenzo Librandi, Sep 29 2015 *)

Prog

(PARI) lista(nn) = forprime(p=2, nn, if (isprime(p + p%9), print1(p, ", "))); \\ Michel Marcus, Sep 12 2015
(Magma) [p: p in PrimesUpTo(2000) | IsPrime(p+(p mod 9))]; // Vincenzo Librandi, Sep 29 2015

Crossrefs

Cf. A000040, A010888, A038194.

Sequence in context: A158759 A107645 A106014 * A289490 A056251 A222805

Adjacent sequences: A261368 A261369 A261370 * A261372 A261373 A261374

Keyword

nonn,base

Author

Gary Croft, Sep 11 2015

Status

approved