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 A121969 #13 Aug 28 2025 17:24:07
%S A121969 954,1980,2961,3870,5823,7641,9108,19980,29880,29961,32760,38970,
%T A121969 39780,49680,49842,54270,58923,59580,60273,60732,69462,69480,69723,
%U A121969 70254,73260,76941,79344,79380,89226,89280,89604,90810,91908,96732,99108
%N A121969 Numbers k such that if you subtract k-reversed from k you get a natural number with the same digits as k.
%D A121969 David Wells, The Penguin Dictionary of Curious and Interesting Numbers (Rev. ed. 1997), p. 154 (entry for 1980).
%H A121969 Harvey P. Dale, <a href="/A121969/b121969.txt">Table of n, a(n) for n = 1..1000</a>
%e A121969 954 - 459 = 495, 19980 - 8991 = 10989.
%t A121969 srdQ[n_]:=Module[{idn=IntegerDigits[n],rn},rn=FromDigits[Reverse[idn]];n>rn&&Sort[IntegerDigits[n-rn]]==Sort[idn]]; Select[Range[100000], srdQ] (* _Harvey P. Dale_, Jun 21 2013 *)
%o A121969 (PARI) isok(n) = {my(d = digits(n)); diff = my(n - subst(Polrev(d), x, 10)); (diff > 0) && (vecsort(digits(diff)) == vecsort(d));} \\ _Michel Marcus_, Sep 04 2015
%Y A121969 Cf. A055161.
%K A121969 base,nonn,changed
%O A121969 1,1
%A A121969 _Tanya Khovanova_, Sep 04 2006