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A216192 a(n) = Smallest m >= 5 containing no twos when represented in any base from 3 through n. 12

%I #25 Mar 18 2016 03:30:51

%S 9,12,28,28,28,28,28,31

%N a(n) = Smallest m >= 5 containing no twos when represented in any base from 3 through n.

%C If a(11) exists, it contains over 3000 digits.

%C No more terms < 10^154400. Most likely there are no more terms. - _Chai Wah Wu_, Mar 17 2016

%H Nathan Fox, <a href="/A216192/a216192.txt">Maple Program to compute a(n)</a>

%e In base 3, 5=12, 6=20, 7=21, 8=22, 9=100. The first representation containing no twos is that of 9, so a(3)=9.

%t Table[SelectFirst[Range[5, 10^3], Total@ Map[Function[k, DigitCount[#, k, 2]], Range[3, n]] == 0 &], {n, 3, 20}] /. n_ /; MissingQ@ n -> Nothing (* _Michael De Vlieger_, Mar 09 2016, Version 10.2 *)

%Y Cf. A216194, A270037, A270038, A270039, A270040, A270041, A270042, A270043, A270044, A270045.

%K nonn,hard,more,base

%O 3,1

%A _Nathan Fox_, Mar 12 2013

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