OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..19
EXAMPLE
21871 is a member as it is a concatenation of 2187 (= 3^7) and 1.
MATHEMATICA
Select[Table[10*3^n+1, {n, 0, 300}], PrimeQ](* Vincenzo Librandi, Dec 08 2011 *)
PROG
(Magma) [a: n in [0..200] | IsPrime(a) where a is 10*3^n + 1]; // Vincenzo Librandi, Dec 08 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Mar 05 2002
EXTENSIONS
More terms from Sascha Kurz, Mar 17 2002
STATUS
approved