OFFSET
1,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
MATHEMATICA
Select[Range[300], PrimeQ[FromDigits[Join[{9}, IntegerDigits[#], {9}]]]&] (* Harvey P. Dale, Jul 20 2012 *)
PROG
(Python)
from sympy import isprime
def ok(n): return isprime(int('9' + str(n) + '9'))
print([k for k in range(250) if ok(k)]) # Michael S. Branicky, Sep 04 2022
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, May 15 1998
STATUS
approved