OFFSET
1,1
LINKS
Jens Kruse Andersen, Table of n, a(n) for n = 1..10000
EXAMPLE
159 is included because 1159159159159 is a prime.
MATHEMATICA
cQ[n_, i_]:=Module[{idn=IntegerDigits[n]}, PrimeQ[FromDigits[Flatten[ Join[ {1}, Table[ idn, {i}]]]]]]; Select[Range[2000], cQ[#, 4]&]
PROG
(Python)
from sympy import isprime
for n in range(10**3):
..if isprime('1'+4*str(n)):
....print(n, end=', ')
# Derek Orr, Aug 17 2014
(PARI) s=[]; for(n=1, 10^4, d=length(Str(n)); if(isprime(10^(4*d)+(10^(4*d)-1)/(10^d-1)*n), s=concat(s, n))); s \\ Jens Kruse Andersen, Aug 18 2014
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Harvey P. Dale, Aug 17 2014
STATUS
approved