1,3

Also numbers n such that (4*10^(n+1)-13)/9 is prime.

Index entries for primes involving repunits

Do[ If[ PrimeQ[ 40*(10^n - 1)/9 + 3], Print[n]], {n, 0, 5000}]

Sequence in context: A129300 A107679 A018846 this_sequence A135050 A004112 A024815

Adjacent sequences: A056658 A056659 A056660 this_sequence A056662 A056663 A056664

hard,more,nonn

Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 09 2000