1,2

Also numbers n such that (4*10^n+41)/9 is prime.

Index entries for primes involving repunits

Do[ If[ PrimeQ[ 4(10^n - 1)/9 + 5], Print[n]], {n, 5000}]

Adjacent sequences: A099411 A099412 A099413 this_sequence A099415 A099416 A099417

Sequence in context: A103022 A086189 A137082 this_sequence A099744 A024601 A085090

nonn,more

Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 14 2004