%I

%S 1,2,14,20,30,44,66,260,872,8846,26744,57506,98472

%N Numbers n such that 4*10^n-3 is prime.

%C See Kamada link for search limit and prime vs. PRP status.

%C a(14) > 10^5. - _Robert Price_, Mar 17 2015.

%H Makoto Kamada, <a href="http://stdkmd.com/nrr/3/39997.htm#prime">Prime numbers of the form 399...997</a>.

%H <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.

%F a(n) = A101849(n) + 1.

%e n = 1, 2, 14, 20 are members since 37, 397, 399999999999997 and 399999999999999999997

%e are prime numbers.

%t Do[ If[ PrimeQ[4*10^n - 3], Print[n]], {n, 0, 10000}]

%Y Cf. A089675, A101849.

%K nonn

%O 1,2

%A Julien Peter Benney (jpbenney(AT)ftml.net), Jan 15 2005

%E a(11)-a(12) from Kamada data by _Robert Price_, Dec 13 2010

%E a(13) from Kamada data by _Robert Price_, Mar 17 2015