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 A104610 #2 Mar 30 2012 17:31:12
%S A104610 1,3,1,1,4,1,2,3,1,0,1,1,1,1,1,3,1,1,0,2,2,4,2,3,2,3,3,0,4,4,5,5,5,5,
%T A104610 1,1,0,3,1,2,3,2,1,1,2,4,3,5,4,4,1,1,5,3,2,5,3,1,2,2,2,0,4,1,0,5,2,3,
%U A104610 0,1,3,0,1,3,3,3,4,0,4,1,0,1,4,4,3,3,2,5,3,0,5,5,2,4,2,0,4,5,4,0,1,1,1,4,1
%N A104610 Write the natural numbers in base 6 in a triangle with k digits in the k-th row, as shown below. Sequence gives the leading diagonal.
%C A104610 1
%C A104610 23
%C A104610 451
%C A104610 0111
%C A104610 21314
%C A104610 152021...
%t A104610 t = Flatten[ IntegerDigits[ Range[1500], 6]]; t[[Table[n(n + 1)/2, {n, 105}]]]
%Y A104610 Cf. A104606, A104607, A104608, A104609, A104611, A104612, A104613, A091425, A104614, A104615, A104616, A104617, A104618, A104619, A104620.
%K A104610 base,nonn
%O A104610 1,2
%A A104610 _Robert G. Wilson v_, Mar 16 2005