This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A051818 #4 Jun 11 2014 17:24:22
%S A051818 1,3,14,86,666,6418,64079,597445,5116146,40671872,304752986,
%T A051818 2187716324,15395364971,110611591118,866239098731,7907500662596
%N A051818 Number of n-digit numbers with nonzero multiplicative digital root 7.
%D A051818 William Mayne, sci.math, Jun 15 1991
%F A051818 # { i : 10^(n-1) < i < 10^n and A051802(i)=7 }
%Y A051818 Cf. A051802, A051809, A051827.
%K A051818 nonn,base,hard
%O A051818 1,2
%A A051818 _Dan Hoey_, Dec 09 1999