OFFSET
1,1
COMMENTS
The next term a(6) has 109 digits and is too large to be displayed here.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..10
Makoto Kamada, Prime numbers of the form 411...11.
MATHEMATICA
Select[Table[FromDigits[PadRight[{4}, n, 1]], {n, 1000}], PrimeQ] (* Harvey P. Dale, Sep 15 2019 *)
PROG
(PARI) for(n=1, 200, if(isprime(4*10^n+(10^(n)-1)/9)==1, print1(4*10^n+(10^(n)-1)/9, ", ")))
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Amarnath Murthy, Mar 07 2002
EXTENSIONS
More terms from Benoit Cloitre, Mar 09 2002
STATUS
approved