OFFSET
1,1
COMMENTS
This sequence is infinite, a consequence of the Prime Number Theorem in arithmetic progressions. - Charles R Greathouse IV, Sep 26 2012
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
EXAMPLE
8 and 21 are in the sequence because 283 and 2213 are primes.
MATHEMATICA
v={}; Do[If[PrimeQ[FromDigits[Join[{2}, IntegerDigits[n], {3}]]], v=Append[v, n]], {n, 260}]; v (* Farideh Firoozbakht, Jun 15 2003 *)
Select[Range[210], PrimeQ[FromDigits[Join[{2}, IntegerDigits[#], {3}]]]&] (* Harvey P. Dale, May 02 2012 *)
PROG
(PARI) for( n=1, 300, isprime(eval(Str(2, n, 3))) & print1(n", ")) \\ M. F. Hasler, Mar 18 2008
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, May 15 1998
EXTENSIONS
Merged with data from duplicate entry A092114. - M. F. Hasler, Mar 18 2008
STATUS
approved