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 A183177 #20 Jan 17 2019 13:44:08
%S A183177 1,7,85,94,273,356,1077,1797,6758,30232
%N A183177 Numbers n such that (10^(2n+1)+15*10^n-1)/3 is prime.
%C A183177 a(11) > 10^5. - _Robert Price_, Apr 21 2016
%D A183177 C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
%H A183177 Patrick De Geest, World!Of Numbers, <a href="http://www.worldofnumbers.com/wing.htm#pwp383">Palindromic Wing Primes (PWP's)</a>
%H A183177 Makoto Kamada, <a href="https://stdkmd.net/nrr/3/33833.htm#prime">Prime numbers of the form 33...33833...33</a>
%H A183177 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F A183177 a(n) = (A077792(n)-1)/2.
%t A183177 Do[If[PrimeQ[(10^(2n + 1) + 15*10^n - 1)/3], Print[n]], {n, 3000}]
%o A183177 (PARI) is(n)=ispseudoprime((10^(2*n+1)+15*10^n-1)/3) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y A183177 Cf. A004023, A077775-A077798, A107123-A107127, A107648, A107649, A115073, A183174-A183187.
%K A183177 nonn,more,base
%O A183177 1,2
%A A183177 _Ray Chandler_, Dec 28 2010
%E A183177 a(10) from _Robert Price_, Apr 21 2016