

A109137


Numbers k such that k * (10^k  1) + 1 is prime.


0




OFFSET

1,1


COMMENTS

Larger values certified with ECM. No more up to 6000.


LINKS



PROG

(Python)
from sympy import isprime
def afind(limit, startk=1):
k, pow10 = startk, 10**startk
for k in range(startk, limit+1):
if isprime(k*(pow10  1) + 1): print(k, end=", ")
k += 1
pow10 *= 10


CROSSREFS



KEYWORD

more,nonn


AUTHOR



EXTENSIONS



STATUS

approved



