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 A257197 #20 Mar 24 2022 18:22:18
%S A257197 116,146,1116,1146,1156,1246,1465,1556,1616,3516,3621,4611,4621,4631,
%T A257197 11116,11146,11156,11465,11556,11642,15216,16231,21556,22631,25146,
%U A257197 25162,25621,33516,34156,35116,35146,35162,36211,36215,36512,46111,46112,46211,46331
%N A257197 Numbers k such that the decimal expansions of both k and k^2 have 1 as smallest digit and 6 as largest digit.
%H A257197 Felix Fröhlich, <a href="/A257197/b257197.txt">Table of n, a(n) for n = 1..10000</a>
%t A257197 sd1Q[n_]:=Module[{idn=IntegerDigits[n]},Min[idn]==1&&Max[idn]==6]; Select[ Range[50000],AllTrue[{#,#^2},sd1Q]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Nov 22 2020 *)
%o A257197 (PARI) is(n) = vecmin(digits(n))==1 && vecmin(digits(n^2))==1 && vecmax(digits(n))==6 && vecmax(digits(n^2))==6
%Y A257197 Cf. A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257210, A257211.
%K A257197 base,nonn
%O A257197 1,1
%A A257197 _Felix Fröhlich_, Apr 18 2015
%E A257197 Corrected b-file from _Felix Fröhlich_, Mar 18 2022