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 A068958 #9 Oct 24 2018 15:06:47 %S A068958 3,1,3,8,9,11,14,0,0,0,0,23,0,29,30,0,0,4,0,0,22,48,2,17,0,54,56,21, %T A068958 65,4,23,74,0,39,0,83,0,89,90,0,96,49,0,15,111,0,114,116,0,15,25,128, %U A068958 131,134,0,0,14,0,73,0,0,156,0,55,168,0,58,16,0,183,93,189,191,194,0,100 %N A068958 Smallest value of k such that p | (10^k + 1), where p is the n-th prime; or 0 if no such k exists. %H A068958 Charles R Greathouse IV, <a href="/A068958/b068958.txt">Table of n, a(n) for n = 4..10000</a> %e A068958 a(4) = 3 as the fourth prime 7 divides 1001. %o A068958 (PARI) a(n)=my(p=prime(n),m=Mod(1,p)); for(k=1,znorder(10*m), if(-1==m*=10, return(k))); 0 \\ _Charles R Greathouse IV_, Jun 18 2013 %K A068958 nonn %O A068958 4,1 %A A068958 _Amarnath Murthy_, Apr 01 2002 %E A068958 More terms from _Sascha Kurz_, Jan 03 2003