OFFSET
1,1
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
EXAMPLE
If k=91 then 1111k = 111191 (prime).
MATHEMATICA
Select[Range[720], PrimeQ[1111*10^IntegerLength[#] + #] &] (* Michael De Vlieger, Jan 22 2018 *)
PROG
(Magma) [ n: n in [1..1750] | IsPrime(Seqint(Intseq(n) cat [1, 1, 1, 1])) ]; // Vincenzo Librandi, Feb 02 2011
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Parthasarathy Nambi, Sep 14 2005
STATUS
approved