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 A069800 #10 Mar 15 2023 11:13:30
%S A069800 1,2,11,3,12,21,111,4,13,22,31,112,121,211,1111,5,14,23,32,41,113,122,
%T A069800 131,212,221,311,1112,1121,1211,2111,11111,6,15,24,33,42,51,114,123,
%U A069800 132,141,213,222,231,312,321,411,1113,1122,1131,1212,1221,1311,2112,2121
%N A069800 Triangular array in which n-th row consists of numbers with digit sum n arranged in increasing numerical order.
%C A069800 0 is not allowed as a digit.
%C A069800 Row n has A104144(n+8) terms. - _T. D. Noe_, Oct 27 2008
%H A069800 T. D. Noe, <a href="/A069800/b069800.txt">Rows n=1..11 of triangle, flattened</a>
%e A069800 Triangle begins:
%e A069800 1;
%e A069800 2,11;
%e A069800 3,12,21,111;
%e A069800 4,13,22,31,112,121,211,1111;
%e A069800 ...
%t A069800 Flatten[Table[p=Partitions[n,9]; Sort[Flatten[Table[FromDigits/@Permutations[p[[i]]], {i,Length[p]}]]], {n,6}]] (* _T. D. Noe_, Oct 27 2008 *)
%Y A069800 Cf. A069801.
%Y A069800 Cf. A007953. [_T. D. Noe_, Oct 27 2008]
%K A069800 nonn,tabf,base
%O A069800 1,2
%A A069800 _Amarnath Murthy_, Apr 13 2002
%E A069800 More terms from _T. D. Noe_, Oct 27 2008