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 A004684 #20 Dec 07 2018 19:35:24 %S A004684 2,3,5,7,10,12,16,18,21,27,29,34,38 %N A004684 Primes written in base 11. (Next term contains a nondecimal character.) %H A004684 Jianing Song, <a href="/A004684/a004684.txt">Table of n, a(n) for n = 1..1000</a> (using A to represent 10) %t A004684 FromDigits /@ TakeWhile[Array[IntegerDigits[Prime@ #, 11] &, 15], NoneTrue[#, # > 9 &] &] (* _Michael De Vlieger_, Nov 25 2018 *) %o A004684 (PARI) a(n)=subst(Pol(digits(prime(n),11)),'x,10) \\ _Charles R Greathouse IV_, Nov 06 2013 %o A004684 (PARI) a(n) = my(d=digits(prime(n), 11)); my(s="", x); for(i=1, #d, if(d[i]<10, x = d[i], x = "A"); s = concat(s, x)); eval(s); %o A004684 for(n=1, 30, print1(a(n), ", ")) \\ _Michel Marcus_, Nov 25 2018 %K A004684 nonn,easy,base %O A004684 1,1 %A A004684 _N. J. A. Sloane_