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A257498 Numbers n such that the decimal expansions of both n and n^2 have 3 as the digit with the smallest value and 8 as the digit with the largest value. 7

%I #14 Sep 18 2017 21:53:42

%S 7378,66834,67438,67738,73874,86356,577378,577438,586374,658388,

%T 666834,667438,676438,683874,683876,684438,688374,738474,738538,

%U 743878,744538,744738,747378,747438,763844,764438,765738,766384,863388,863474,873874,874378,875434

%N Numbers n such that the decimal expansions of both n and n^2 have 3 as the digit with the smallest value and 8 as the digit with the largest value.

%H Chai Wah Wu, <a href="/A257498/b257498.txt">Table of n, a(n) for n = 1..10000</a>

%t fQ[n_] := Block[{c = DigitCount@ n}, And[Plus @@ Take[c, {1, 2}] == 0, Plus @@ Take[c, {9, 10}] == 0, c[[3]] > 0, c[[8]] > 0]]; Select[Range@ 1000000, fQ@ # && fQ[#^2] &] (* _Michael De Vlieger_, May 05 2015 *)

%o (PARI) is(n) = vecmin(digits(n))==3 && vecmin(digits(n^2))==3 && 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, A238553, A257534.

%K nonn,base

%O 1,1

%A _Felix Fröhlich_, Apr 27 2015

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Last modified March 28 08:12 EDT 2024. Contains 371236 sequences. (Running on oeis4.)