%I #8 Dec 05 2013 19:57:03
%S 6,55,550,5500,55000,550000,5500000,55000000,550000000,5500000000,
%T 55000000000,550000000000,5500000000000,55000000000000,
%U 550000000000000,5500000000000000,55000000000000000,550000000000000000,5500000000000000000
%N Average of positive multiples of 3 with n decimal digits, rounded down.
%C Subsidiary sequence: Average of positive multiples of k with n decimal digits, rounded down.
%F For n > 1, a(n+1) = 10 * a(n).
%e a(2) = average {12,15,...96,99} = floor((12+99)/2) = 55.
%o (PARI) a(n)=(11*10^(n1)+1)\2
%Y Cf. A110430.
%K nonn,base
%O 1,1
%A _Amarnath Murthy_, Aug 02 2005
%E Corrected and extended by _Joshua Zucker_, May 10 2006
%E Formula and program from _Charles R Greathouse IV_, Aug 03 2010
