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 A102930 #26 Feb 01 2023 23:07:08
%S A102930 1,2,4,14,25,32,56,62,811,812,1084,2533,11924,49552
%N A102930 Numbers k such that 10^k + 2*R_k + 5 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
%C A102930 Also numbers k such that (11*10^k + 43)/9 is prime.
%C A102930 a(15) > 10^5. - _Robert Price_, Jan 16 2015
%C A102930 a(15) > 2*10^5. - _Tyler Busby_, Feb 01 2023
%H A102930 Makoto Kamada, <a href="https://stdkmd.net/nrr/1/12227.htm#prime">Prime numbers of the form 122...227</a>.
%H A102930 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F A102930 a(n) = A102010(n) + 1.
%t A102930 Do[ If[ PrimeQ[(11*10^n + 43)/9], Print[n]], {n, 0, 10000}]
%Y A102930 Cf. A002275, A102010.
%K A102930 more,nonn
%O A102930 1,2
%A A102930 _Robert G. Wilson v_, Dec 16 2004
%E A102930 Addition of a(13) from Kamada data by _Robert Price_, Dec 12 2010
%E A102930 a(14) from Erik Branger May 01 2013 by _Ray Chandler_, Aug 16 2013