%I
%S 31,3001,30000001,30000000001,30000000000000000000000000001,
%T 3000000000000000000000000000000000001,
%U 30000000000000000000000000000000000000000000000000000000000000000001
%N Primes of the form 3*10^n + 1.
%H S. W. Golomb, <a href="http://www.jstor.org/stable/2005337">Properties of the sequence 3.2^n+1</a>, Math. Comp., 30 (1976), 657663.
%H S. W. Golomb, <a href="/A004119/a004119.pdf">Properties of the sequence 3.2^n+1</a>, Math. Comp., 30 (1976), 657663. [Annotated scanned copy]
%F a(n) = 3*10^A056807(n)+1.  _R. J. Mathar_, Jul 15 2015
%Y Cf. A199683, A056807.
%K nonn
%O 1,1
%A _N. J. A. Sloane_, Jul 08 2015
