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 A223090 #9 Jun 29 2025 15:07:17
%S A223090 21,189,525,567,1134,1365,1533,4599,4725,9198,10773,12285,34125,36855,
%T A223090 38325,73710,86037,87381,96957,98301,269325,294903,307125,589806,
%U A223090 688149,700245,774333,786429,2150925,2184525,2322999,2359287,2423925,2457525,4645998,4718574,5505045,5515797,5592405,5603157,6193341,6204093,6280701,6291453
%N A223090 Numbers k with the property that if the base-8 representation of k is read backwards, the result is an integral multiple of k.
%C A223090 A217742 is a subsequence.
%C A223090 The multiples that occur are 2, 3, 5, 7 (cf. A222817-A222820).
%e A223090 n = 525 (base 10) = 1015 (base 8). Reading this backwards we get 5101 (base 8) = 2625 (base 10) = 5*n, so 525 is in the sequence.
%t A223090 b8rQ[n_]:=Module[{c=FromDigits[Reverse[IntegerDigits[n,8]],8]},c/n>1 && IntegerQ[c/n]]; Select[Range[63*10^5],b8rQ] (* _Harvey P. Dale_, Sep 18 2016 *)
%Y A223090 Cf. A214927, A217742, A223089, A222817-A222820.
%K A223090 nonn,base
%O A223090 1,1
%A A223090 _N. J. A. Sloane_, Mar 23 2013