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 A110680 #11 Jan 20 2024 16:02:50 %S A110680 9,21,43,49,61,63,69,73,87,109,127,147,159,169,171,201,207,213,217, %T A110680 229,241,261,289,291,331,339,357,369,381,397,409,469,471,483,487,507, %U A110680 519,549,591,607,621,639,663,669,697,703,711,717,729,747 %N A110680 Numbers k such that the string 4444k is prime. %H A110680 Harvey P. Dale, <a href="/A110680/b110680.txt">Table of n, a(n) for n = 1..1000</a> %e A110680 k=109 is in the sequence because 4444k = 4444109 is prime. %t A110680 Select[Range[800],PrimeQ[4444*10^IntegerLength[#]+#]&] (* _Harvey P. Dale_, Jul 04 2014 *) %K A110680 nonn,base %O A110680 1,1 %A A110680 _Parthasarathy Nambi_, Sep 14 2005