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Numbers n such that largest digit of all divisors of n is 1.
2

%I #16 Jul 16 2014 15:34:53

%S 1,11,101,1111,10111,101111,1011001,1100101,10010101,10011101,

%T 10100011,10101101,10110011,10111001,11000111,11100101,11110111,

%U 11111101,100100111,100111001,101001001,101001011,101100011,101101111,101111011,101111111,110010101

%N Numbers n such that largest digit of all divisors of n is 1.

%C Also numbers n such that largest digit of concatenation of all divisors (A037278) of n is 1.

%C What is the smallest n with a(n) <> A203304(n)? - _Alois P. Heinz_, Jul 16 2014

%H Alois P. Heinz, <a href="/A209930/b209930.txt">Table of n, a(n) for n = 1..8503</a>

%e Number 1111 is in sequence because largest digit of all divisors of 1111 (1, 11, 101, 1111) is 1.

%t t = {}; n = 0; While[Length[t] < 30, n++; m = FromDigits[IntegerDigits[n, 2]]; If[Max[Union[Flatten[IntegerDigits[Divisors[m]]]]] <= 1, AppendTo[t, m]]]; t (* _T. D. Noe_, Jan 30 2013 *)

%Y Cf. A209928 (largest digit of all divisors of n).

%Y Cf. A203304.

%K nonn,base

%O 1,2

%A _Jaroslav Krizek_, Mar 20 2012

%E Corrected by _Jaroslav Krizek_, Jan 29 2013