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A113560 Least multiple of n in which the n-th digit from left is 5.

%I A113560 #11 Mar 15 2024 17:56:20
%S A113560 5,150,105,10052,10005,1000050,1000055,100000056,100000035,
%T A113560 10000000050,10000000065,1000000000056,1000000000025,100000000000054,
%U A113560 100000000000005,10000000000000256,10000000000000135,1000000000000000152,1000000000000000075,1000000000000000000500
%N A113560 Least multiple of n in which the n-th digit from left is 5.
%H A113560 Robert Israel, <a href="/A113560/b113560.txt">Table of n, a(n) for n = 1..995</a>
%e A113560 a(4) = 4 * 2513 = 10052, in which the fourth digit is 5.
%p A113560 f:= proc(n) local d,m,R,v;
%p A113560     for d from n do
%p A113560       R:= {};
%p A113560       for m from ceil(10^(d-1)/n) do
%p A113560         v:= m*n;
%p A113560         if v > 10^d then break fi;
%p A113560         v:= v mod 10^(d-n+1);
%p A113560         if member(v,R) then break fi;
%p A113560         if floor(v/10^(d-n)) = 5 then return m*n fi;
%p A113560         R:= R union {v};
%p A113560       od
%p A113560     od;
%p A113560 end proc:
%p A113560 map(f, [$1..30]); # _Robert Israel_, Mar 15 2024
%Y A113560 Cf. A113556, A113557, A113558, A113559.
%K A113560 base,easy,nonn
%O A113560 1,1
%A A113560 _Amarnath Murthy_, Nov 06 2005
%E A113560 More terms from _Joshua Zucker_, May 03 2006