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 A002964 #22 Feb 16 2025 08:32:27
%S A002964 1,2,3,7,8,17,18,27,28,37,38,87,88,187,188,287,288,387,388,788,887,
%T A002964 888,1388,1788,1887,1888,2388,2788,2887,2888,3388,3788,3887,3888
%N A002964 Smallest number requiring n chisel strokes for its representation in Roman numerals.
%C A002964 A002963(a(n)) = n. - _Reinhard Zumkeller_, Apr 14 2013
%H A002964 Harvey P. Dale, <a href="/A002964/b002964.txt">Table of n, a(n) for n = 1..10000</a>
%H A002964 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RomanNumerals.html">Roman Numerals</a>
%H A002964 Wikipedia, <a href="http://en.wikipedia.org/wiki/Roman_numerals">Roman numerals</a>
%t A002964 DeleteDuplicates[Table[{n,Total[Characters[RomanNumeral[n]]/.{"L"->2,"X"->2,"V"->2,"I"->1,"M"->4,"C"->2,"D"->3}]},{n,4000}],GreaterEqual[#1[[2]],#2[[2]]]&][[;;,1]] (* _Harvey P. Dale_, Jan 19 2025 *)
%o A002964 (Haskell)
%o A002964 a002964 = (+ 1) . fromJust . (`elemIndex` (map a002963 [1..3888]))
%o A002964 -- _Reinhard Zumkeller_, Apr 14 2013
%Y A002964 Cf. A002963.
%K A002964 base,nonn,nice
%O A002964 1,2
%A A002964 _N. J. A. Sloane_
%E A002964 More terms from _Erich Friedman_
%E A002964 For n>13: data corrected and completed up to A002963(3888)=34 by _Reinhard Zumkeller_, Apr 14 2013