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 A108159 #11 Feb 16 2025 08:32:58
%S A108159 3,160,812
%N A108159 Numbers n such that (initial n digits of decimal expansion of 1/243)-1 is prime.
%H A108159 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/243.html">243</a>.
%t A108159 Do[ If[ PrimeQ[ Floor[10^n/243 - 1]], Print[n]], {n, 8000}] (* _Robert G. Wilson v_, Jun 10 2005 *)
%o A108159 (PARI) for(n=1,999,if(isprime(floor(1/243*10^n)-1),print1(n",")))
%Y A108159 Cf. A021247.
%K A108159 more,nonn,base,bref,dumb
%O A108159 1,1
%A A108159 _Jason Earls_, Jun 07 2005