OFFSET
1,2
COMMENTS
11 and 13 are twin primes.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
n=1: 11131 is prime.
n=47: 111347 is prime.
n=149: 1113149 is prime.
MATHEMATICA
Select[Range[800], PrimeQ[1113*10^IntegerLength[#]+#]&] (* Harvey P. Dale, Sep 26 2016 *)
PROG
(Magma) [ n: n in [1..800] | IsPrime(Seqint(Intseq(n) cat [3, 1, 1, 1])) ];
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Parthasarathy Nambi, Jun 09 2005
STATUS
approved