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 A263478 #26 Oct 25 2015 06:59:19
%S A263478 1,9,55,214,615,1451,3829,60180,939045,8732485,56961531,289887214,
%T A263478 1229099287,4756606869,24218431805,233925901576,2661527233449,
%U A263478 25685325408201,203451565638511,1356903584035110,7832822232934951,40022453239462639,184228949831881593
%N A263478 Total number of n-digit positive integers with multiplicative digital root value 4.
%C A263478 First differences of A263472.
%H A263478 Hiroaki Yamanouchi, <a href="/A263478/b263478.txt">Table of n, a(n) for n = 1..50</a>
%F A263478 A263476(n) + A000012(n) + A263477(n) + A000027(n) + a(n) + A263479(n) + A263480(n) + A000027(n) + A263481(n) + A000217(n) = A052268(n).
%t A263478 Last /@ Tally@ IntegerLength@ Select[Range@ 1000000, FixedPoint[Times @@ IntegerDigits@ # &, #] == 4 &] (* _Michael De Vlieger_, Oct 21 2015 *)
%o A263478 (PARI) t(k) = {while(k>9, k=prod(i=1, #k=digits(k), k[i])); k}
%o A263478 a(n) = sum(i=10^(n-1), 10^n - 1, if(t(i) == 4, 1, 0)); \\ _Altug Alkan_, Oct 19 2015
%Y A263478 Cf. A031347, A034051, A263472.
%K A263478 nonn,base
%O A263478 1,2
%A A263478 _Martin Renner_, Oct 19 2015
%E A263478 a(9)-a(23) from _Hiroaki Yamanouchi_, Oct 25 2015