# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/

Search: id:a102959
Showing 1-1 of 1

%I A102959 #19 Jan 17 2019 13:44:07
%S A102959 1,4,34,36,42,52,163,208,216,1417,14646,22794,25648,32515,51421
%N A102959 Numbers n such that 2*10^n + 7*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
%C A102959 Also numbers n such that (25*10^n+11)/9 is prime.
%C A102959 a(16) > 10^5. - _Robert Price_, Mar 12 2015
%H A102959 Makoto Kamada, <a href="https://stdkmd.net/nrr/2/27779.htm#prime">Prime numbers of the form 277...779</a>.
%H A102959 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F A102959 a(n) = A101968(n) + 1.
%t A102959 Do[ If[ PrimeQ[(25*10^n + 11)/9], Print[n]], {n, 0, 10000}]
%Y A102959 Cf. A002275, A101968.
%K A102959 more,nonn
%O A102959 1,2
%A A102959 _Robert G. Wilson v_, Dec 17 2004
%E A102959 a(11)-a(13) from Kamada data by _Robert Price_, Dec 14 2010
%E A102959 a(14) from Erik Branger May 01 2013 by _Ray Chandler_, Aug 16 2013
%E A102959 a(15) from _Robert Price_, Mar 12 2015

# Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE