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 A077788 #43 Dec 06 2023 18:25:14
%S A077788 9,11,17,23,2489,3371,4019,29315,30237,40665,101661,150125
%N A077788 Numbers k such that 7*(10^k - 1)/9 - 10^floor(k/2) is a palindromic wing prime (a.k.a. near-repdigit palindromic prime).
%C A077788 Prime versus probable prime status and proofs are given in the author's table.
%D A077788 C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
%H A077788 Patrick De Geest, World!Of Numbers, <a href="http://www.worldofnumbers.com/wing.htm#pwp767">Palindromic Wing Primes (PWP's)</a>
%H A077788 Makoto Kamada, <a href="https://stdkmd.net/nrr/7/77677.htm#prime">Prime numbers of the form 77...77677...77</a>
%H A077788 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F A077788 a(n) = 2*A183181(n) + 1.
%e A077788 11 is a term because 7*(10^11 - 1)/9 - 10^5 = 77777677777.
%t A077788 Do[ If[ PrimeQ[(7*10^n - 9*10^Floor[n/2] - 7)/9], Print[n]], {n, 3, 30300, 2}] (* _Robert G. Wilson v_, Dec 16 2005 *)
%Y A077788 Cf. A004023, A077775-A077798, A107123-A107127, A107648, A107649, A115073, A183174-A183187.
%K A077788 more,nonn,base
%O A077788 1,1
%A A077788 _Patrick De Geest_, Nov 16 2002
%E A077788 Name corrected by _Jon E. Schoenfield_, Oct 31 2018
%E A077788 a(10) from _Robert Price_, Oct 07 2023
%E A077788 a(11) from _Robert Price_, Oct 17 2023
%E A077788 a(12) from _Robert Price_, Dec 06 2023