A167216 Primes whose reversal - 1 is also prime.

3, 23, 41, 47, 83, 89, 233, 251, 257, 281, 401, 461, 491, 809, 821, 827, 839, 857, 863, 887, 2003, 2069, 2081, 2099, 2153, 2213, 2237, 2267, 2333, 2351, 2381, 2393, 2399, 2477, 2591, 2633, 2657, 2711, 2741, 2753, 2789, 2819, 2879, 2909, 2939, 2957, 2963

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Example

23 is in the sequence because 23 is prime and 32 - 1 = 31 is prime.

Maple

reverse:= proc(n)
local L, j;
L:= convert(n, base, 10);
add(L[j]*10^(nops(L)-j), j=1..nops(L))
end proc:
select(n -> isprime(n) and isprime(reverse(n)-1), [$1..10000]); # Robert Israel, Jul 11 2014

Mathematica

Select[Prime[Range[5000]], PrimeQ[FromDigits[Reverse[IntegerDigits[#]]] - 1] &] (* Vincenzo Librandi, Jul 11 2014 *)

Prog

(Magma) [p: p in PrimesInInterval(2, 3000) | IsPrime(q-1) where q is Seqint(Reverse(Intseq(p)))]; // Vincenzo Librandi, Jul 11 2014
(Python)
from sympy import isprime, primerange
def ok(p): return isprime(int(str(p)[::-1]) - 1)
print([p for p in primerange(1, 3000) if ok(p)]) # Michael S. Branicky, Mar 23 2021
(PARI) isok(p) = isprime(p) && isprime(fromdigits(Vecrev(digits(p)))-1); \\ Michel Marcus, Mar 23 2021

Crossrefs

Cf. similar sequences listed in A243457.

Sequence in context: A116893 A106066 A281551 * A309935 A212396 A319976

Adjacent sequences: A167213 A167214 A167215 * A167217 A167218 A167219

Keyword

nonn,base

Author

Claudio Meller, Oct 30 2009

Extensions

Comment changed to an Example by Robert Israel, Jul 11 2014

Status

approved