A051827 - OEIS

%I #4 Jun 11 2014 17:24:23

%S 1,4,18,104,770,7188,71267,668712,5784858,46456730,351209716,

%T 2538926040,17934291011,128545882129,994784980860,8902285643456

%N Number of numbers below 10^n with nonzero multiplicative digital root 7.

%C Conjectured o(10^n)

%D William Mayne, sci.math, Jun 15 1991

%F # { i : 10^(n-1) < i < 10^n and A051802(i)=7 }

%Y Cf. A051802, A051809, A051818.

%K nonn,base,hard

%O 1,2

%A _Dan Hoey_, Dec 09 1999