This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A095714 #35 Jul 08 2021 05:04:55
%S A095714 3,5,7,33,45,105,197,199,281,301,317,1107,1657,3395,35925,37597,64305,
%T A095714 80139,221631
%N A095714 Numbers k such that 9*R_k - 8 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
%C A095714 Also numbers k such that 10^k - 9 is a prime.
%H A095714 Makoto Kamada, <a href="https://stdkmd.net/nrr/9/99991.htm#prime">Prime numbers of the form 99...991</a>.
%H A095714 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>
%F A095714 a(n) = A056696(n) + 1.
%e A095714 a(2) = 5, since 10^5 - 9 = 99991, which is prime.
%t A095714 Do[ If[ PrimeQ[10^n - 9], Print[n]], {n, 0, 7000}]
%Y A095714 Cf. A002275, A093177, A056696.
%K A095714 nonn
%O A095714 1,1
%A A095714 _Alonso del Arte_, Jul 07 2004
%E A095714 a(12) - a(14) from _Robert G. Wilson v_, Oct 15 2004
%E A095714 a(15) - a(16) from _Jason Earls_, Jan 07 2008
%E A095714 a(17) - a(19) from _Alexander Gramolin_, May 13 2011
%E A095714 Edited by _Ray Chandler_, Feb 26 2012
%E A095714 Title corrected by _Robert Price_, Sep 06 2014