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 A256633 #13 Feb 06 2025 13:27:29
%S A256633 60,160,460,506,560,600,601,602,605,660,1006,1016,1060,1160,1460,1560,
%T A256633 1600,1601,1602,1620,2006,2016,2060,2160,2460,2560,3606,4506,4600,
%U A256633 4605,4650,5006,5016,5060,5160,5506,5600,5605,5660,6000,6001,6002,6005,6010,6020
%N A256633 Numbers n such that the decimal expansions of both n and n^2 have 0 as smallest digit and 6 as largest digit.
%H A256633 Felix Fröhlich, <a href="/A256633/b256633.txt">Table of n, a(n) for n = 1..10000</a>
%t A256633 fQ[n_] := Block[{c = DigitCount@ n}, And[Plus @@ Take[c, {7, 9}] == 0, c[[6]] > 0, c[[10]] > 0]]; Select[Range@ 6400, fQ@ # && fQ[#^2] &] (* _Michael De Vlieger_, Apr 12 2015 *)
%t A256633 Select[Range[6100],With[{idn=IntegerDigits[#],idn2=IntegerDigits[#^2]},Min[idn]==Min[idn2]==0&&Max[idn]==Max[idn2]==6]&] (* _Harvey P. Dale_, Feb 06 2025 *)
%o A256633 (PARI) is(n) = vecmin(digits(n))==0 && vecmin(digits(n^2))==0 && vecmax(digits(n))==6 && vecmax(digits(n^2))==6
%Y A256633 Cf. A256630, A256631, A256634, A256708, A256709, A256889, A257085.
%K A256633 nonn,base
%O A256633 1,1
%A A256633 _Felix Fröhlich_, Apr 05 2015