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 A077793 #41 Aug 03 2024 18:57:56
%S A077793 3,7,79,109,337,481,10657,12319,49351,104455,227775
%N A077793 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 A077793 Prime versus probable prime status and proofs are given in the author's table.
%D A077793 C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
%H A077793 Patrick De Geest, World!Of Numbers, <a href="http://www.worldofnumbers.com/wing.htm#pwp787">Palindromic Wing Primes (PWP's)</a>
%H A077793 Makoto Kamada, <a href="https://stdkmd.net/nrr/7/77877.htm#prime">Prime numbers of the form 77...77877...77</a>
%H A077793 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F A077793 a(n) = 2*A183182(n) + 1.
%e A077793 7 is a term because 7*(10^7 - 1)/9 + 10^3 = 7778777.
%t A077793 Do[ If[ PrimeQ[(7*10^n + 9*10^Floor[n/2] - 7)/9], Print[n]], {n, 3, 12400, 2}] (* _Robert G. Wilson v_, Dec 16 2005 *)
%Y A077793 Cf. A004023, A077775-A077798, A107123-A107127, A107648, A107649, A115073, A183174-A183187.
%K A077793 more,nonn,base
%O A077793 1,1
%A A077793 _Patrick De Geest_, Nov 16 2002
%E A077793 Name corrected by _Jon E. Schoenfield_, Oct 31 2018
%E A077793 a(9) from _Robert Price_, Oct 07 2023
%E A077793 a(10) from _Robert Price_, Oct 30 2023
%E A077793 a(11) from _Robert Price_, Aug 03 2024