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%I #18 Sep 12 2017 02:41:55
%S 684,6684,8874,66684,68474,74758,76478,86478,666684,668474,675684,
%T 744758,766458,6666684,6668474,6675684,6748678,6845784,7586478,
%U 8686574,8875684,66666684,66756684,74744758,74758576,75858874,75867574,76464878,86878458,87546878
%N Numbers n such that the decimal expansions of both n and n^2 have 4 as the digit with the smallest value and 8 as the digit with the largest value.
%H Chai Wah Wu, <a href="/A254071/b254071.txt">Table of n, a(n) for n = 1..1000</a>
%t fQ[n_] := Block[{c = DigitCount@ n}, And[Plus @@ Take[c, {1, 3}] == 0, Plus @@ Take[c, {9, 10}] == 0, c[[4]] > 0, c[[8]] > 0]]; Select[Range@ 1000000, fQ@ # && fQ[#^2] &] (* _Michael De Vlieger_, May 05 2015 *)
%o (PARI) is(n) = vecmin(digits(n))==4 && vecmin(digits(n^2))==4 && vecmax(digits(n))==8 && vecmax(digits(n^2))==8
%Y Cf. A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A257211, A256601, A257310, A249915, A257123, A257368, A257485, A257486, A257498, A238553.
%K nonn,base
%O 1,1
%A _Felix Fröhlich_, May 03 2015
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