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A329792 Smallest positive k such that k*n contains only the digits 1,2,3,4,5, or -1 if no such k exists.

%I A329792 #23 Dec 04 2019 10:59:22
%S A329792 -1,1,1,1,1,1,2,2,3,5,-1,1,1,1,1,1,2,2,3,6,-1,1,1,1,1,1,2,2,4,5,-1,1,
%T A329792 1,1,1,1,4,3,3,6,-1,1,1,1,1,1,7,3,3,5,-1,1,1,1,1,1,2,2,4,6,-1,2,2,4,8,
%U A329792 5,2,2,8,5,-1,2,2,7,3,3,2,2,3,7,-1,3,16,4,3,3,4,5,4,5,-1
%N A329792 Smallest positive k such that k*n contains only the digits 1,2,3,4,5, or -1 if no such k exists.
%C A329792 a(n) > 0 iff n is not a multiple of 10.
%D A329792 G. Galperin  and Y. J. Ionin (Proposers), and M. Reid (Solver), Problem 12034, Amer. Math. Monthly, 126:10, 950-951, Dec. 2019.
%H A329792 Rémy Sigrist, <a href="/A329792/b329792.txt">Table of n, a(n) for n = 0..25000</a>
%o A329792 (Python)
%o A329792 def A329792(n):
%o A329792     if n % 10:
%o A329792         m, s = 1, set('12345')
%o A329792         while not set(str(m*n)) <= s:
%o A329792             m += 1
%o A329792         return m
%o A329792     else:
%o A329792         return -1 # _Chai Wah Wu_, Dec 04 2019
%Y A329792 Cf. A084545, A329793.
%K A329792 sign,look,base
%O A329792 0,7
%A A329792 _N. J. A. Sloane_, Dec 03 2019