%N a(n) contains the nonzero frequencies f(d) of digits d=0 .. 9 in all terms up to a(n-1) in concatenated form sorted with respect to d: f(0)//0//f(1)//1//...//f(9)//9. Initial term a(1)=4.
%C For a Mathematica program, see A177360 (you have to slightly modify it) [From Jasper Mulder (jasper.mulder(AT)planet.nl), Jun 04 2010]
%H J. Mulder, <a href="/A177363/b177363.txt">Table of n, a(n) for n = 1..25000</a>
%e Four; one four; one one, two fours; three ones, one two, three fours; five ones, two twos, two threes, four fours; six ones, five twos, three threes, six fours, one five; etc.
%Y Cf. A060857, A177359 - A177368.
%A _Paolo P. Lava_ and _Giorgio Balzarotti_, May 10 2010