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 A014643 #16 May 17 2018 10:24:30
%S A014643 1,1,1,2,1,2,2,1,2,2,3,3,1,2,2,3,3,4,4,4,5,5,5,1,2,2,3,3,4,4,4,5,5,5,
%T A014643 6,6,6,6,7,7,7,7,8,8,8,8,9,9,9,9,9,10,10,10,10,10,11,11,11,11,11
%N A014643 Triangular array starting with {1,1}; then i-th term in a row gives number of i's in next row.
%C A014643 The row {2} could be safely prepended to this triangle. - _Gus Wiseman_, May 13 2018
%H A014643 Alois P. Heinz, <a href="/A014643/b014643.txt">Rows n = 1..8, flattened</a>
%e A014643 Triangle begins:
%e A014643 {1,1},
%e A014643 {1,2},
%e A014643 {1,2,2},
%e A014643 {1,2,2,3,3},
%e A014643 ...
%p A014643 T:= proc(n) option remember; `if`(n=0, 2, (l->
%p A014643 seq(i$l[i], i=1..nops(l)))([T(n-1)]))
%p A014643 end:
%p A014643 seq(T(n), n=1..7); # _Alois P. Heinz_, May 17 2018
%t A014643 NestList[Join@@Table[Table[i,{#[[i]]}],{i,Length[#]}]&,{2},8] (* _Gus Wiseman_, May 13 2018 *)
%Y A014643 Rows converge to A001462.
%Y A014643 Cf. A011784, A012257, A014643, A014644, A112798, A181819, A182850-A182858, A296150, A304455.
%K A014643 tabf,nonn
%O A014643 1,4
%A A014643 _N. J. A. Sloane_
%E A014643 More terms from _Patrick De Geest_