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 A078814 #25 Feb 21 2025 08:23:00 %S A078814 17,1433,499679,1279,31,149 %N A078814 Smallest prime factor of googolplex - n that exceeds 13, or 1 if googolplex - n is 13-smooth. %C A078814 Seventh term is not known. Sequence continues ?, 625392489737, 19, 37, 5419, 107, 23, 60149, 1733, 89, 8543, 17, 5261, 229, 8656871, 4273, 14009, 29, 509, 43628661784403, 24539783, 19, 347, 12414692011, 523, 151, 421, 35816135619181, 17, 23, 184309, ?, 181, 288481, 163, 41, 743, 13337, 71, 53, 19, 59, 113, 37957721, ... where the unknown numbers exceed 25 * 10^12. - _Dario Alpern_, Jul 03 2003 %H A078814 Dario Alejandro Alpern, <a href="https://www.alpertron.com.ar/GOOGOLM.HTM">Factors of 1000 numbers up to googolplex</a>. %t A078814 (* For any individual n *) k = 17; While[ !PrimeQ[k] || PowerMod[10, 10^100, k] - n != 0, k += 2]; k %o A078814 (PARI) a(n) = forprime(p=17, oo, if(Mod(10, p)^lift(Mod(10, p-1)^100) == n, return(p))); \\ _Jinyuan Wang_, Apr 17 2020 %Y A078814 Cf. A072288, A200924, A227247. %K A078814 nonn,hard,more,fini %O A078814 1,1 %A A078814 _Ed Pegg Jr_ and _Robert G. Wilson v_, Dec 06 2002 %E A078814 Name edited by _Peter Munn_, Feb 20 2025