A321523 List of pairs: primes whose reversal is also prime, each followed by its reversal.

2, 2, 3, 3, 5, 5, 7, 7, 11, 11, 13, 31, 17, 71, 31, 13, 37, 73, 71, 17, 73, 37, 79, 97, 97, 79, 101, 101, 107, 701, 113, 311, 131, 131, 149, 941, 151, 151, 157, 751, 167, 761, 179, 971, 181, 181, 191, 191, 199, 991, 311, 113, 313, 313, 337, 733, 347, 743, 353, 353

Offset: 1

Author

Kritsada Moomuang, Nov 12 2018

Keywords

• nonn
• base
• tabf

Examples

			The sequence begins:
     2,  2;
     3,  3;
     5,  5;
     7,  7;
    11, 11;
    13, 31;
    17, 71;
    31, 13;
    37, 73;
    71, 17;
...
107 has its reversal as 701.
971 has its reversal as 179.
		

Crossrefs

Subsequence of A135020.

Cf. A000040, A004086, A007500, A095180, A180022.

Programs

Mathematica

Flatten@ Table[ If[PrimeQ[r = IntegerReverse@ p], {p,r}, {}], {p, Prime@ Range@ 71}] (* Giovanni Resta, Nov 13 2018 *)

PARI

forprime(p=1, 353, r=fromdigits(Vecrev(digits(p))); if (isprime(r), print1(p ", " r ", "))) \\ Rémy Sigrist, Nov 16 2018

Formula

a(2n-1) = A007500(n).

a(2n) = A004086(A007500(n)).

a(2n) = A095180(n). - Rémy Sigrist, Nov 16 2018