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 A173204 #11 Mar 09 2022 01:14:23
%S A173204 7,1,20,9,17,19,24,19,91,94,93,101,104,103,111,115,113,117,124,123,
%T A173204 173,923,973,1101,1104,1103,1111,1115,1113,1117,1124,1123,1173,1323,
%U A173204 1373,9323,9373,17373,19173,19323,19373,91373,93323
%N A173204 a(n) is the smallest number which has in its English name the letter "n" in the n-th position beginning the count from the end.
%e A173204 a(1) = seveN, a(2) = oNe, a(3) = tweNty, a(4)= Nine, a(5) = seveNteen, etc.
%t A173204 ePos[n_] := Flatten@Position[DeleteCases[Reverse@Characters@IntegerName[n, "Words"], a_ /; MemberQ[{" ", "\[Hyphen]"}, a]], "n"]; t = {}; i = 1; Monitor[Table[Do[If[MemberQ[ePos[i], n], Return[lst = AppendTo[t, i]; i = 1; lst], i++], \[Infinity]], {n, 1, 43, 1}] // Last, {ProgressIndicator[n, {1, 43}], n, i}] (* _Robert P. P. McKone_, Feb 07 2022 *)
%Y A173204 Cf. A164791 ("n" in n-th position),.
%Y A173204 Cf. A173203 (similar for "e"), A173206 (similar for "t").
%K A173204 nonn,word
%O A173204 1,1
%A A173204 _Claudio Meller_, Feb 12 2010
%E A173204 More terms from _Robert P. P. McKone_, Feb 08 2022