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 A062891 #23 Jun 15 2021 09:54:39
%S A062891 0,1,2,3,6,9,13,18,26,27,34,39,47,54,78,81,91,102,117,121,141,162,182,
%T A062891 234,242,243,262,273,306,351,363,423,486,546,702,726,729,757,786,819,
%U A062891 918,1048,1053,1089,1093,1183,1269,1458,1514,1638,2106,2178,2186,2187
%N A062891 When expressed in base 3 and then interpreted in base 9, is a multiple of the original number.
%H A062891 Harvey P. Dale, <a href="/A062891/b062891.txt">Table of n, a(n) for n = 1..751</a> [offset shifted by _Georg Fischer_, Jun 15 2021]
%e A062891 13 in base 3 is 111, which interpreted in base 9 is 91 = 7*13.
%p A062891 q:= n-> (l-> n=0 or 0=irem(add(l[i]*9^(i-1),
%p A062891 i=1..nops(l)), n))(convert(n, base, 3)):
%p A062891 select(q, [$0..3000])[]; # _Alois P. Heinz_, Apr 20 2021
%t A062891 Join[{0},Select[Range[2200],Divisible[FromDigits[IntegerDigits[#,3],9],#]&]] (* _Harvey P. Dale_, Apr 11 2017 *)
%Y A062891 Cf. A007089 (base 3), A007095 (base 9), A037314 (base 3 -> 9).
%Y A062891 Other digit spreads: A062846 (binary), A343550 (decimal).
%K A062891 base,nonn
%O A062891 1,3
%A A062891 _Erich Friedman_, Jul 21 2001
%E A062891 Offset changed to 1 by _Kevin Ryde_, Apr 24 2021