OFFSET
1,1
COMMENTS
Primes which with a 1 appended stay prime.
Corresponding values of 10n + 1 in A055781. - Jaroslav Krizek, Jul 14 2010
Subsequence of A024912. - Michel Marcus, May 21 2014
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MAPLE
with(numtheory); for i from 1 to 500 do if isprime(10*ithprime(i)+1) then printf(`%d, `, ithprime(i)) fi: od: # James A. Sellers, Apr 09 2005
MATHEMATICA
Select[Prime[Range[ 240]], PrimeQ[FromDigits[Join[IntegerDigits[ # ], {1}]]] &] (* Robert G. Wilson v, Apr 09 2005 *)
Select[Prime[Range[900]], PrimeQ[10 # + 1] &] (* Vincenzo Librandi, May 21 2014 *)
PROG
(Magma) [n: n in [0..1000] | IsPrime(n) and IsPrime(10*n+1)] // Vincenzo Librandi, Nov 20 2010
(Magma) [p: p in PrimesUpTo(1100)| IsPrime(10*p+1)]; // Vincenzo Librandi, May 21 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Edited by N. J. A. Sloane at the suggestion of M. F. Hasler, Aug 24 2007
STATUS
approved