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 A351894 #10 Feb 26 2022 10:11:10
%S A351894 1,3,9,21,33,45,81,93,153,165,201,213,393,405,441,453,633,645,681,693,
%T A351894 873,885,921,933,1113,1125,1161,1173,1353,1365,1401,1413,2313,2325,
%U A351894 2361,2373,2553,2565,2601,2613,2793,2805,2841,2853,3753,3765,3801,3813,3993,4005
%N A351894 Numbers that contain only odd digits in their factorial-base representation.
%C A351894 All the terms above 1 are odd multiples of 3.
%H A351894 Amiram Eldar, <a href="/A351894/b351894.txt">Table of n, a(n) for n = 1..18056</a> (terms below 11!)
%H A351894 Wikipedia, <a href="https://en.wikipedia.org/wiki/Factorial_number_system">Factorial number system</a>.
%H A351894 <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a>.
%e A351894 3 is a term since its factorial-base presentation, 11, has only odd digits.
%e A351894 21 is a term since its factorial-base presentation, 311, has only odd digits.
%t A351894 max = 7; fctBaseDigits[n_] := IntegerDigits[n, MixedRadix[Range[max, 2, -1]]]; Select[Range[1, max!, 2], AllTrue[fctBaseDigits[#], OddQ] &]
%Y A351894 Cf. A007623, A016945, A351893.
%Y A351894 Subsequence: A007489
%Y A351894 Similar sequences: A003462 \ {0} (ternary), A014261 (decimal), A032911 (base 4), A032912 (base 5), A033032 (base 6), A033033 (base 7), A033034 (base 8), A033035 (base 9), A033036 (base 11), A033037 (base 12), A033038 (base 13), A033039 (base 14), A033040 (base 15), A033041 (base 16), A126646 (binary).
%K A351894 nonn,base
%O A351894 1,2
%A A351894 _Amiram Eldar_, Feb 24 2022