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 A128244 #13 Dec 09 2016 03:50:14
%S A128244 1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,0,2,3,4,5,6,7,8,9,0,1,3,4,5,6,7,
%T A128244 8,9,0,1,2,4,5,6,7,8,9,0,1,2,3,5,6,7,8,9,0,1,2,3,4,6,7,8,9,0,1,2,3,4,
%U A128244 5,7,8,9,0,1,2,3,4,5,6,8,9,0,1,2,3,4,5,6,7,9,0,1,2,3,4,5,6,7,8,1,2,3,4,5,6
%N A128244 Let s be the sum of the digits of n; a(n) is the product of the digits of s.
%C A128244 The sequence is equal to A053837 up to the 488th term.
%H A128244 Robert Israel, <a href="/A128244/b128244.txt">Table of n, a(n) for n = 1..10000</a>
%F A128244 a(n) = A007954(A007953(n)). - _Michel Marcus_, Dec 09 2016
%e A128244 a(345)=2 because 3+4+5=12 and 1*2=2.
%p A128244 P:=proc(n) local i,k,w; for i from 1 by 1 to n do w:=0; k:=i; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; k:=w; w:=1; while k>0 do w:=w*(k-(trunc(k/10)*10)); k:=trunc(k/10); od; print(w); od; end: P(500);
%p A128244 # alternative
%p A128244 f:= n -> convert(convert(convert(convert(n,base,10),`+`),base,10),`*`):
%p A128244 map(f, [$1..100]); # _Robert Israel_, Dec 09 2016
%t A128244 sdpd[n_]:=Module[{s=Total[IntegerDigits[n]]},Times@@IntegerDigits[s]]; Array[sdpd, 110] (* _Harvey P. Dale_, Dec 17 2013 *)
%Y A128244 Cf. A053837, A007953, A007954.
%K A128244 easy,nonn,base
%O A128244 1,2
%A A128244 _Paolo P. Lava_ and _Giorgio Balzarotti_, May 03 2007
%E A128244 Offset corrected by _Robert Israel_, Dec 09 2016