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%I #10 Oct 14 2022 14:55:54
%S 128,178,871,1128,1178,1218,1258,1278,1284,1328,1358,1368,1478,1678,
%T 1681,1768,1778,1784,1785,1828,1874,1881,2681,2861,2871,3418,3581,
%U 3718,3816,3841,4178,4318,4815,4831,4841,4881,5178,5181,5182,5318,5815,5841,5871,5881
%N Numbers n such that the decimal expansions of both n and n^2 have 1 as smallest digit and 8 as largest digit.
%H Felix Fröhlich, <a href="/A257211/b257211.txt">Table of n, a(n) for n = 1..10000</a>
%t fQ[n_] := Block[{d = DigitCount@ n}, Plus @@ Take[d, {9, 10}] == 0 && d[[1]] > 0 && d[[8]] > 0]; Select[Range@ 6000, fQ@ # && fQ[#^2] &] (* _Michael De Vlieger_, Apr 20 2015 *)
%t sd1ld8Q[n_]:=With[{idn=IntegerDigits[n]},Max[idn]==8&&Min[idn]==1]; Select[ Range[ 6000],AllTrue[{#,#^2},sd1ld8Q]&] (* _Harvey P. Dale_, Oct 14 2022 *)
%o (PARI) is(n) = vecmin(digits(n))==1 && vecmin(digits(n^2))==1 && vecmax(digits(n))==8 && vecmax(digits(n^2))==8
%Y Cf. A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A256601.
%K nonn,base
%O 1,1
%A _Felix Fröhlich_, Apr 18 2015