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 A118639 #19 Feb 09 2025 19:38:28 %S A118639 1,4,9,40,90,400,900,4000,9000,40000,90000,400000,900000 %N A118639 Smallest number expressible using the next Roman-numeral symbol under the vinculum system. %H A118639 Wikipedia, <a href="http://en.wikipedia.org/wiki/Roman_numerals">Roman numerals</a> %e A118639 a(1) = I (first usage of I); %e A118639 a(2) = IV (first usage of V); %e A118639 a(3) = IX (first usage of X); %e A118639 a(4) = XL (first usage of L); %e A118639 a(5) = XC (first usage of C); %e A118639 a(6) = CD (first usage of D); %e A118639 a(7) = CM (first usage of M). %Y A118639 Cf. A003587, A118640. %K A118639 easy,nonn,base,fini,full %O A118639 1,2 %A A118639 _Greg Huber_, May 09 2006