

A166501


Primes p such that (p reversed)+4 is also a prime.


5



3, 7, 31, 73, 79, 97, 313, 331, 349, 379, 397, 541, 571, 709, 739, 757, 769, 937, 967, 3037, 3061, 3067, 3121, 3163, 3187, 3217, 3229, 3253, 3313, 3319, 3361, 3433, 3457, 3529, 3547, 3613, 3631, 3643, 3673, 3739, 3769, 3847, 3889, 5011, 5023, 5101, 5107
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


LINKS



FORMULA



EXAMPLE

73 is in the sequence because 37+4=41 prime.
331 is in the sequence because 133+4=137 prime.
3457 is in the sequence because 7543+4=7547 prime.


MATHEMATICA

Select[Prime[Range[700]], PrimeQ[FromDigits[Reverse[IntegerDigits[#]]]+ 4]&] (* Harvey P. Dale, May 21 2012 *)
Select[Prime[Range[700]], PrimeQ[IntegerReverse[#]+4]&] (* Harvey P. Dale, Mar 16 2023 *)


PROG

(Magma) [p: p in PrimesUpTo(6000)  IsPrime(q+4) where q is Seqint(Reverse(Intseq(p)))]; // Vincenzo Librandi, Sep 15 2013


CROSSREFS



KEYWORD

nonn,base,less


AUTHOR



EXTENSIONS

Keyword:base added, 3163 inserted, sequence extended by R. J. Mathar, Oct 16 2009


STATUS

approved



