A103071 - OEIS

%I #17 Jan 17 2019 13:44:07

%S 1,10,24,199,745,7753,17938,21319,24948,26119,29454,51889,62824,88105

%N Numbers n such that 8*10^n + R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

%C Also numbers n such that (73*10^n+17)/9 is prime.

%C a(15) > 10^5. - _Robert Price_, Oct 16 2015

%H Makoto Kamada, <a href="https://stdkmd.net/nrr/8/81113.htm#prime">Prime numbers of the form 811...113</a>.

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

%F a(n) = A101058(n) + 1.

%t Do[ If[ PrimeQ[(73*10^n + 17)/9], Print[n]], {n, 0, 10000}]

%Y Cf. A002275, A101058.

%K more,nonn

%O 1,2

%A _Robert G. Wilson v_, Jan 19 2005

%E a(7)-a(11) from Kamada data by _Robert Price_, Dec 14 2010

%E a(12)-a(14) from _Robert Price_, Oct 16 2015