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 A216812 Smallest positive number divisible by n whose decimal expansion has the form 22...200...0. 2

%I

%S 2,2,222,20,20,222,222222,200,222222222,20,2222222222,2220,

%T 222222222222,222222,2220,2000,2222222222222222,222222222,

%U 222222222222222222,20,222222

%N Smallest positive number divisible by n whose decimal expansion has the form 22...200...0.

%F If n=3^k, a(n)=2(10^n-1)/9. For all n, a(n) <= 2(10^n-1)/9.

%F a(2^k)= 2*10^(k-1).

%F If p=prime, a(p) = 2(10^(p-1)-1)/9.

%Y Cf. A078241, A216481.

%K nonn,base

%O 1,1

%A _N. J. A. Sloane_, Sep 18 2012

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Last modified December 7 03:00 EST 2019. Contains 329836 sequences. (Running on oeis4.)