OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
tcat:= (a, b) -> a*10^(1+ilog10(b))+b:
select(t -> isprime(tcat(t, t+9)), [seq(i, i=2..1000, 2)]); # Robert Israel, Sep 04 2024
MATHEMATICA
Select[Range[400], PrimeQ[FromDigits[Join[IntegerDigits[#], IntegerDigits[#+9]]]]&] (* Stefano Spezia, Sep 04 2023 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, May 15 1998
STATUS
approved