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

2, 2, 222, 20, 20, 222, 222222, 200, 222222222, 20, 2222222222, 2220, 222222222222, 222222, 2220, 2000, 2222222222222222, 222222222, 222222222222222222, 20, 222222

Offset: 1

Author

N. J. A. Sloane, Sep 18 2012

Keywords

• nonn
• base

Crossrefs

Cf. A078241, A216481.

Formula

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

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

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