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 A033930 #18 Feb 12 2017 16:47:21
%S A033930 1,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,10,2,3,4,5,6,7,8,9,10,11,3,4,5,
%T A033930 6,7,8,9,10,11,12,4,5,6,7,8,9,10,11,12,13,5,6,7,8,9,10,11,12,13,14,6,
%U A033930 7,8,9,10,11,12,13,14,15,7,8,9,10,11,12,13,14,15,16,8,9,10,11,12,13,14
%N A033930 Base 10 digital convolution sequence.
%C A033930 Differs from A007953 at n=0, 101-109, 111-119 etc. [_R. J. Mathar_, Oct 20 2008]
%H A033930 Indranil Ghosh, <a href="/A033930/b033930.txt">Table of n, a(n) for n = 0..10000</a>
%F A033930 For example, a(837) = 8*a(2)+3*a(1)+7*a(0).
%t A033930 a = {1}; Do[AppendTo[a, ListConvolve[Reverse@ Take[a, Length@ #], #][[1]] &@ IntegerDigits@ n], {n, 10^3}]; a (* _Michael De Vlieger_, Feb 12 2017 *)
%o A033930 (PARI) a(n) = if (!n, 1, my(d = digits(n)); sum(i=1, #d, d[i]*a(#d-i))); \\ _Michel Marcus_, Sep 13 2014
%K A033930 nonn,base
%O A033930 0,3
%A A033930 _David W. Wilson_